[Mage ST] Need a crash course in Mummy

[Justin Sane]

For my Mage game, I'm planning to have an encounter with one of the Arisen - he's going to be holding a Relic/Artifact which the PCs will need/want for themselves.

My problem is, I know next to nothing about Mummy, and what I do know is what pops up on the Mage forums. That said, that might be a blessing in disguise, as I intend to translate the mechanics to a Mage PoV.

My first question is - would one of the Arisen be willing to "lend out" a Relic, if the PCs prove trustworthy enough?

Second question is - how would you build this Mummy? Bear in mind, I'm more looking for narrative descriptions of its powerset than actual mechanics, but some indication of "how it should work" would also help.

Third question is - how do I make this encounter memorable? What's the thing that should stand out the most? I think I've got the cult nailed down, but the leader should be impressive on its own right.

[Octavo]

Mummy is a game that unites cosmic horror and the horror of being middle management. Mummies work for dread beings that are essentially what Mages would call Akathartoi - unclean beings from the Lower Depths. Every Mummy originates in a craftsman guild in pre-dynastic Egypt, and is summoned periodically from their Lower Depth by their cults to search for relics infused with Sekhem - a sort of life essence. Mummies believe that all relics, whether made by their civilization or not, belong to the Judges of Duat they serve. They seek out these relics and send them into the lower depth for consumption (and occasionally regurgitation.)

Mummies take damage like vampires, but have an inverted death cycle. While Vampires spend most of their time awake unless they're sent into torpor for whatever reason, Mummies are dormant in their tombs unless the tomb is invaded or unless the cult summons them to life. They start out looking dead and gooey with a gnosis equivalent at 10, and as they spend more time "alive", their gnosis equivalent drops. When it hits 0, they fall back into a torpor equivalent. They can slow this descent by obeying the will of the judges or by obeying the reason they were summoned by the cult.

Mummy powers are of two types - affinities (small boosts in power and ability and a few magical tricks), and utterances (massive scale miracles that have 3 tiers of power tied to how high their gnosis equivalent is.) Any of the major effects from the mummy movies can be done with utterances.

TL;DR - Mummies are supervillains with their own minions and secret bases, which they use to commit international heists. They probably would only lend a mage a relic if A. They thought they could get a bigger relic out of the relationship, or B. Strongly believed they'd get the relic back after the Mage helps them out with their task.

[Justin Sane]

Mummy is a game that unites cosmic horror and the horror of being middle management.

Perfect. This fits in my chronicle just right.

Mummies work for dread beings that are essentially what Mages would call Akathartoi - unclean beings from the Lower Depths.

That would be the Judges of Duat, correct? Follow-up question, on a Mage-centric game, could the Judges be misidentified as the Exarchs (or at least, another form of their servants)?

Every Mummy originates in a craftsman guild in pre-dynastic Egypt, and is summoned periodically from their Lower Depth by their cults to search for relics infused with Sekhem - a sort of life essence.

I'm not really interested in going into Mummy society - but I'm curious, the Guilds seems analogous to the Orders, is that correct? Are there powers/philosofies specific to each one? Which do you think would fit my chronicle better?
Also, mental note: Sehkem is a life essence, but is not Life, and is not Essence. Could you elaborate on the specifics?

Mummies believe that all relics, whether made by their civilization or not, belong to the Judges of Duat they serve. They seek out these relics and send them into the lower depth for consumption (and occasionally regurgitation.)

Interesting. I didn't had the notion they were interested in not-Relics - or is it a "as long as it has Sehkem" thing?
As for seeking out Relics and sending them Below - it really feels the Judges and the Exarchs could be two faces of the same coin - or, at least, on the same page.

Mummies take damage like vampires, but have an inverted death cycle. While Vampires spend most of their time awake unless they're sent into torpor for whatever reason, Mummies are dormant in their tombs unless the tomb is invaded or unless the cult summons them to life.They start out looking dead and gooey with a gnosis equivalent at 10, and as they spend more time "alive", their gnosis equivalent drops. When it hits 0, they fall back into a torpor equivalent. They can slow this descent by obeying the will of the judges or by obeying the reason they were summoned by the cult.

I was aware of that, so to make sure the PCs aren't steamrolled completely in case a confrontation happens, I can say the Mummy has been active for a while now. The question then becomes - how fast is their Descent? Let's say around 25-30 years active, would a Gnosis-equivalent (also, what's their Power Stat called?) of 6 be reasonable, considering it has been following a specific order ("Do not let the Dethroned Queen retake her Robe")?

Mummy powers are of two types - affinities (small boosts in power and ability and a few magical tricks), and utterances (massive scale miracles that have 3 tiers of power tied to how high their gnosis equivalent is.) Any of the major effects from the mummy movies can be done with utterances.

Utterances I know Rebuke the Vizier and that one that calls down a meteor - never heard of Affinities, can you give some examples?

TL;DR - Mummies are supervillains with their own minions and secret bases, which they use to commit international heists. They probably would only lend a mage a relic if A. They thought they could get a bigger relic out of the relationship, or B. Strongly believed they'd get the relic back after the Mage helps them out with their task.

So, fits in perfectly with the theme of my chronicle, and can work either as a terrifying antagonist or a strange partner-in-crime. That sounds just lovely, and knowing my players, it's most certainly going to be option A

Thanks for the time typing that out, I really appreciate it.

[Seraph Kitty]

I recently used a mummy in my mage game, so hopefully I have some useful advice for you...

Follow-up question, on a Mage-centric game, could the Judges be misidentified as the Exarchs (or at least, another form of their servants)?

In crossover games, I assume that the goals of the Judges, Exarchs, and Vampire elders are all .... complementary. I wouldn't have them work together, and they might even end up at cross purposes, but in general the way they organize societies are mutually beneficial. It'd be easy to look at some of the things mummies do and compare it to the Seers. Mortal Remains goes into this a little bit, but from an outsider perspective, mummies and their cults trend toward two active purposes: 1) collect and sacrifice magic items, and 2) reshape human culture to perpetuate the same themes and ideas as the last 6 thousand years. If you assume the Status Quo reflects the will of the Exarchs, than mummies are certainly some of the macro-scale movers and shakers that perpetuate it.

But, if you get a good look at a Mummy - such as their sympathetic connections - you might see glimpses of their Judge; and the Judges have pretty horrifying descriptions which are much more in line with Lower Depths (perhaps even Abyssal) appearances. The Exarchs, even at their most horrific, tend to be more human-like or at least more classically archetypal... the Judges are more like dead old gods.
Just from a mummy's actions or even hearing about the decrees of the Judges, they'd probably be pretty easy to mistake from Exarchs. But if you can glimpse the entity pulling their strings, a mage would likely get a very different impression.

I'm not really interested in going into Mummy society - but I'm curious, the Guilds seems analogous to the Orders, is that correct? Are there powers/philosofies specific to each one? Which do you think would fit my chronicle better?

Yes- Guilds are a bit like Orders. In brief, they are
-Second Hands: middle managers and secret police. they foster cooperation, keep the orthodoxy, and are all about manipulating social networks.
-Alchemists: their philosophy is that all things have an intrinsic worth which can be cultivated in different ways. They teach how to gain and use power.
-Necromancers: priests of forbidden knowledge. They seem to be the ones most interested in understanding the Judges and the plan they have for mummies... mostly through experimental necromancy.
-Scribes: historians and arbiters. They actively seek knowledge and correct injustice.
-Builders: monumental architects. They believe the whole world has a "lifeweb" - the pattern Sekhem flows through - and that it is their purpose to reshape its flow with the intent of "organizing" society.

I recommend using a Builder (I think the guild is the "Father of Idols" / Tef Aabhi). They are extremely long-term, big scale thinkers. Their main schemes involve working occult geometry into a city's layout in order to control the resonance of each part, reorganizing the naturally-created mystic energy and applying it to a long term purpose. This plays merry hell with ley lines and the spirit world. It can be the source of many a mystery, as well as a huge point of either conflict or cooperation depending on your goals for the story. In your case, they could have the easy-in of lending out a relic to mages in order to trick them into shaping the lifeweb in a particular way.

Also, mental note: Sehkem is a life essence, but is not Life, and is not Essence. Could you elaborate on the specifics? Interesting. I didn't had the notion they were interested in not-Relics - or is it a "as long as it has Sehkem" thing?

Sekhem is described as the life force, a mystic energy that exists everywhere life (or the potential for life) is. In it's natural state, it is described as a passive force of emotional connectivity, carrying remembered passions of life. I interpret this as Sekhem = Resonance; as such, there is no arcana that it falls under, but Spirit, Prime, and Mind are all related to it, and you can probably see it with Life (as some life spells describe attacking or repairing the "life force").
The relics described in mummy are potent magical items created with intention; a related item mummy's care about (and also collect to sacrifice), vessels, are kind of accidentally created by witnessing intense passions. If you extrapolate this for cross-over purposes, many items from Reliquary and most of the momentos in Geist would count, I should think. They might also take an interest in fetishes and imbued items, but I don't think artifacts quite apply. Although there's nothing to stop you from saying "all magic items belong to the Judges!" and have them seek out anything and everything.

The question then becomes - how fast is their Descent? Let's say around 25-30 years active, would a Gnosis-equivalent (also, what's their Power Stat called?) of 6 be reasonable, considering it has been following a specific order ("Do not let the Dethroned Queen retake her Robe")?

Their power stat is called Sekhem. It actually falls relatively fast: if they lose a level at every scheduled interval, doing nothing to hasten or slow the descent, it lasts roughly 400 days. Assuming they get lucky on a few rolls or keep to their purpose, they will probably stay active for 2 years on average. They'd have to go out of their way with epic accomplishments (killing a greater demon, murdering people in the streets to harken the Judges' law, building enormous works of art dedicated to Irem, etc) or be consuming relics themselves (a blasphemous act) to spend more time active.
Since the descent is on an exponential curve, they've already dropped down to Sekhem 6 after 8.5 days, and are due to drop to Sekhem 5 after 10 more days. Basically, if they've been recently awakened, but had some time to orient, plan, and start getting shit done, they're at Sekhem 6 or less. It goes pretty quick. If they've been around for a while, kicked their cult into motion, and are finalizing plans, have time to work on themselves, are preparing for their long-term plans.. their more likely to be at Sekhem 3 or less.
However, their cult can always raise them again, if they have access to adequate relics. Frequent or frivolous awakenings are highly discouraged (especially because they lose a dot in Memory every time they rise - if they aren't actively working on themselves every Descent, they quickly lose identity), but the cult can call them ~6 months or so, for another 2 year active period. So if you have a highly motivate mummy (who can stave off Memory loss), they might spend every 2/3 years active, but it's more likely for them to rise once every decade or more.

The Purpose their given on an arising tends to require discrete steps to complete. An on-going one like that doesn't really fit with how they work. They'd be more likely to be called to protect the Robe of the Dethroned Queen for a critical period of time, kill the people trying to get it, or reclaim it after its been taken. Essentially, they'd be woken up every time their cult discovers an enemy plot to take it, and return to slumber once that's dealt with.

Utterances I know Rebuke the Vizier and that one that calls down a meteor - never heard of Affinities, can you give some examples?

Quick descriptions of Affinities. They tend to be be rather passive enhancements, boosting their abilities in specific areas due to hyper-energized life force, but some have more obvious supernatural effects.
Quick descriptions of Utterances. In my crossover considerations, I ruled that the source energy of Utterances can be understood with Prime + Fate sight, as they are a form of mortal magic learned from the cosmic forces of Fate - words written into the fabric of reality that command what occurs; obviously their effects can fall under any Arcana though.


Hope that helps,
~Seraph Kitty

[Octavo]

I'd really recommend Princes of the Conquered Land, from Dark Eras Companion. It details the specifics of crossing over Mage and Mummy.

[Second Chances]

I'd really recommend Princes of the Conquered Land, from Dark Eras Companion. It details the specifics of crossing over Mage and Mummy.

Linkified above. Definitely worth checking out.

[Exthalion]

Yes- Guilds are a bit like Orders. In brief, they are
-Second Hands: middle managers and secret police. they foster cooperation, keep the orthodoxy, and are all about manipulating social networks.
-Alchemists: their philosophy is that all things have an intrinsic worth which can be cultivated in different ways. They teach how to gain and use power.
-Necromancers: priests of forbidden knowledge. They seem to be the ones most interested in understanding the Judges and the plan they have for mummies... mostly through experimental necromancy.
-Scribes: historians and arbiters. They actively seek knowledge and correct injustice.
-Builders: monumental architects. They believe the whole world has a "lifeweb" - the pattern Sekhem flows through - and that it is their purpose to reshape its flow with the intent of "organizing" society.

There is also the 6th guild, the Restless Stars, but they are different in several important ways and don't interact with regular mummies.
In the linked sources, Dec and LotD are for them and some of that stuff is not known to regular mummies.

[Azahul]

I believe Dark Eras describes the Mage view of working with Sekhem to be roughly equivalent to working radioactive plutonium with one's bare hands. It's a bit nutso to have a being running on the raw stuff.

I will note that there is one other method wherein a Mummy could have been active for 35-40 years without ending their descent, and that would be if they were awake for a Sothic Turn. This probably isn't the best route to go down, one of the best ways to interact with a Mummy as an antagonist is to identify their Purpose and use that to mess with them indirectly or as leverage to cut deals, and a Sothic Rising means that the Arisen is awake with no purpose and stays at Sekhem 1 until something forces them to lose a Sekhem (death, blasphemy against their Judge, something like that) or they willingly end their descent. It would also mean your Arisen antagonist is likely hovering around the weakest end of the power scale, which probably makes for a less interesting encounter and would mean you wouldn't get to showcase the Descent through having the Mummy appear weaker from encounter to encounter.

[Exthalion]

I believe Dark Eras describes the Mage view of working with Sekhem to be roughly equivalent to working radioactive plutonium with one's bare hands. It's a bit nutso to have a being running on the raw stuff.

I will note that there is one other method wherein a Mummy could have been active for 35-40 years without ending their descent, and that would be if they were awake for a Sothic Turn. This probably isn't the best route to go down, one of the best ways to interact with a Mummy as an antagonist is to identify their Purpose and use that to mess with them indirectly or as leverage to cut deals, and a Sothic Rising means that the Arisen is awake with no purpose and stays at Sekhem 1 until something forces them to lose a Sekhem (death, blasphemy against their Judge, something like that) or they willingly end their descent. It would also mean your Arisen antagonist is likely hovering around the weakest end of the power scale, which probably makes for a less interesting encounter and would mean you wouldn't get to showcase the Descent through having the Mummy appear weaker from encounter to encounter.

With the right setup, a Sekhem 1 mummy in their Tomb could still be very dangerous.

A talisman raises their Sekhem back to 2.
Entombed glory allows them to spend 1 WP and add their defining Pillar (probably 5 for someone this old) to their Sekhem if in their tomb.
So they are Sekhem 7 when they need to be.

Restless Stars don't get talismans, but have an affinity to add up to another 3 so they could theoretically be Sekhem 9 if they need to be.

[Azahul]

With the right setup, a Sekhem 1 mummy in their Tomb could still be very dangerous.

A talisman raises their Sekhem back to 2.
Entombed glory allows them to spend 1 WP and add their defining Pillar (probably 5 for someone this old) to their Sekhem if in their tomb.
So they are Sekhem 7 when they need to be.

Restless Stars don't get talismans, but have an affinity to add up to another 3 so they could theoretically be Sekhem 9 if they need to be.

Oh, I'm aware of all of that. That's all really useful information if you're running Mummy, or interested in playing it. But for someone wanting to use an Arisen as an antagonist with a plan to mod the rules like the OP, that level of nitty gritty isn't necessary and also runs into the trap of misrepresenting the idea of the Mummy. If I want to highlight an NPC Arisen in a game, from a story perspective, you aren't going to capture the descent by having the Arisen be Sekhem 1/2 all the time save spiking to 7 when in their Tomb. That has a very different flavour to encountering an Arisen at Sekhem 10, then a few days later at Sekhem 7, then a week later at Sekhem 4, and so on. The former gives the impression of an undead creature bound to its resting place and granted phenomenal powers when inside, the latter allows you as a Storyteller to actually show the Descent to an external audience.

[Azahul]

Edit: Double post.

[Vent0]

Oh, I'm aware of all of that. That's all really useful information if you're running Mummy, or interested in playing it. But for someone wanting to use an Arisen as an antagonist with a plan to mod the rules like the OP, that level of nitty gritty isn't necessary and also runs into the trap of misrepresenting the idea of the Mummy. If I want to highlight an NPC Arisen in a game, from a story perspective, you aren't going to capture the descent by having the Arisen be Sekhem 1/2 all the time save spiking to 7 when in their Tomb. That has a very different flavour to encountering an Arisen at Sekhem 10, then a few days later at Sekhem 7, then a week later at Sekhem 4, and so on. The former gives the impression of an undead creature bound to its resting place and granted phenomenal powers when inside, the latter allows you as a Storyteller to actually show the Descent to an external audience.

Of course, nothing says you can't combine the two - a Mummy foe that weakens as time goes on... until the PCs try to end the mummy in their Tomb and find their mojo is back (at least partially).

[Azahul]

Of course, nothing says you can't combine the two - a Mummy foe that weakens as time goes on... until the PCs try to end the mummy in their Tomb and find their mojo is back (at least partially).

That would certainly get around the worrying potential for an anti-climactic finale. I'd be leery of pulling this without appropriate foreshadowing, of course, as reversing the Descent right at the end might be considered cheap to players who aren't aware that there exists some potential for this kind of thing.

There are other ways to make for a dramatic finale, however. There is a general expectation, though not one enforced by the mechanics, that a weak Arisen will have raised their Memory a few dots since their awakening. That means that they may have remembered and gained access to an increasingly large collection of relics, allies, and important facts that may help them handle the situation. Doing so transforms the nature of the Arisen threat over the course of their descent, but conceptually I like the route of the sinister being whose influence grows even as the physical/mystical threat they pose declines. Or, if your PCs end up embracing the "strange allies" possibility, then this method would allow them to experience their new friend changing from a mystical heavyweight who has their back in physical confrontations to a puppet master with impossible foreknowledge who can open all kinds of doors for them politically.

But generally speaking, I think it would be good if you could arrange for the PCs to have their first encounter, ideally a non-violent one since a violent one has the potential to go sideways fast, with the Arisen within hours of their awakening. If you want the Arisen to have been working towards a goal for decades, that is better attributed to past descents (which have the added fun that the Mummy may not realise what they themselves want for a while) and/or the machinations of their cult.

[SunlessNick]

Guilds seems analogous to the Orders, is that correct? Are there powers/philosofies specific to each one? Which do you think would fit my chronicle better?

The scribes, second hands, and necromancers are probably too concerned with mummy-specific matters. The builders are interested in the magical landscape in a way that makes them likely to cross paths with other supernaturals - plus they have cool statuary and architecture, which is good for the imagery. The alchemists would be a good match for materialist or deal-making mages - they believe in a concept called dedwen, which is as if value was an energy - worth cannot be created and destroyed, only transformed.

Also, mental note: Sehkem is a life essence, but is not Life, and is not Essence. Could you elaborate on the specifics?

It's life force, but not just biological life - also experiental life, in the sense of "this life I have lived." The emotional connections between people, objects, and the world are all expressions of Sekhem. I don't know if you have the Reliquary blue-book supplement, but while the relics in that - and how they come to be what they are - aren't explicitly powered by Sekhem, they are a perfect fit for it.

Interesting. I didn't had the notion they were interested in not-Relics - or is it a "as long as it has Sehkem" thing?

Like everyone else, mummies can be prone to seeing everything through their lens, and assuming that any magical artefact is like theirs. They might also be right, in the sense that only the most utilitarian such items are unlikely to be imbued with emotional meaning for their creators or owners - and that meaning could imbue it with Sekhem, even if that is completely orthogonal to its other functions and energies. It probably won't be a lot of Sekhem, though, so even mummies that are interested in them might not prioritise them.

As for seeking out Relics and sending them Below - it really feels the Judges and the Exarchs could be two faces of the same coin - or, at least, on the same page.

If mages can get a look at Sekhem somehow (via a weird Life/Matter/Mind combo, probably), they would probably be able to tell it's an energy of this world, not the Supernal or the Abyss. That makes it reasonable to suspect that wherever the relics and their Sekhem are sent is a Lower Depth - just taking the energy, not the source of it. On the other hand, yes, the Judges and Exarchs do seem to have a lot in common when it comes to how they want the world to be.

[Justin Sane]

Thanks for the replies, everyone. I just need clarifications on a few points.

But, if you get a good look at a Mummy - such as their sympathetic connections - you might see glimpses of their Judge; and the Judges have pretty horrifying descriptions which are much more in line with Lower Depths (perhaps even Abyssal) appearances. The Exarchs, even at their most horrific, tend to be more human-like or at least more classically archetypal... the Judges are more like dead old gods.
Just from a mummy's actions or even hearing about the decrees of the Judges, they'd probably be pretty easy to mistake from Exarchs. But if you can glimpse the entity pulling their strings, a mage would likely get a very different impression.

Outside the Mummy corebook, where could I get some inspiration for their visuals? Is the Hall of Dead Gods, from American Gods, a good ballpark?

Yes- Guilds are a bit like Orders. In brief, they are
-Second Hands: middle managers and secret police. they foster cooperation, keep the orthodoxy, and are all about manipulating social networks.
-Alchemists: their philosophy is that all things have an intrinsic worth which can be cultivated in different ways. They teach how to gain and use power.
-Necromancers: priests of forbidden knowledge. They seem to be the ones most interested in understanding the Judges and the plan they have for mummies... mostly through experimental necromancy.
-Scribes: historians and arbiters. They actively seek knowledge and correct injustice.
-Builders: monumental architects. They believe the whole world has a "lifeweb" - the pattern Sekhem flows through - and that it is their purpose to reshape its flow with the intent of "organizing" society.

I recommend using a Builder (I think the guild is the "Father of Idols" / Tef Aabhi). They are extremely long-term, big scale thinkers. Their main schemes involve working occult geometry into a city's layout in order to control the resonance of each part, reorganizing the naturally-created mystic energy and applying it to a long term purpose. This plays merry hell with ley lines and the spirit world. It can be the source of many a mystery, as well as a huge point of either conflict or cooperation depending on your goals for the story. In your case, they could have the easy-in of lending out a relic to mages in order to trick them into shaping the lifeweb in a particular way.

The scribes, second hands, and necromancers are probably too concerned with mummy-specific matters. The builders are interested in the magical landscape in a way that makes them likely to cross paths with other supernaturals - plus they have cool statuary and architecture, which is good for the imagery. The alchemists would be a good match for materialist or deal-making mages - they believe in a concept called dedwen, which is as if value was an energy - worth cannot be created and destroyed, only transformed.

Hmm. While the Builders do seem interesting, I'd really prefer this was a one-time thing. The Necromancers, on the other hand, seem to fit in just fine (and thanks for reminding me about WoDCodex, who know Mummies had so many powers related to ghosts?), especially because the Moros PC hasn't been using Death recently.

Sekhem is described as the life force, a mystic energy that exists everywhere life (or the potential for life) is. In it's natural state, it is described as a passive force of emotional connectivity, carrying remembered passions of life. I interpret this as Sekhem = Resonance; as such, there is no arcana that it falls under, but Spirit, Prime, and Mind are all related to it, and you can probably see it with Life (as some life spells describe attacking or repairing the "life force").

I believe Dark Eras describes the Mage view of working with Sekhem to be roughly equivalent to working radioactive plutonium with one's bare hands. It's a bit nutso to have a being running on the raw stuff.

It's life force, but not just biological life - also experiental life, in the sense of "this life I have lived." The emotional connections between people, objects, and the world are all expressions of Sekhem. I don't know if you have the Reliquary blue-book supplement, but while the relics in that - and how they come to be what they are - aren't explicitly powered by Sekhem, they are a perfect fit for it.

Okay, yeah, that plus the bit in Princes of the Conquered Land (thanks Octavo and Second Chances) made it click for me.

The relics described in mummy are potent magical items created with intention; a related item mummy's care about (and also collect to sacrifice), vessels, are kind of accidentally created by witnessing intense passions. If you extrapolate this for cross-over purposes, many items from Reliquary and most of the momentos in Geist would count, I should think. They might also take an interest in fetishes and imbued items, but I don't think artifacts quite apply. Although there's nothing to stop you from saying "all magic items belong to the Judges!" and have them seek out anything and everything.

Like everyone else, mummies can be prone to seeing everything through their lens, and assuming that any magical artefact is like theirs. They might also be right, in the sense that only the most utilitarian such items are unlikely to be imbued with emotional meaning for their creators or owners - and that meaning could imbue it with Sekhem, even if that is completely orthogonal to its other functions and energies. It probably won't be a lot of Sekhem, though, so even mummies that are interested in them might not prioritise them.

Yeah, the Cabal's Obsessions boil down to "Build a Magical Hoard", so an inclusive approach works best. Plus, the Robe of the Dethroned Queen is anything but utilitarian, and, as of right now, not really Supernal.

Their power stat is called Sekhem. It actually falls relatively fast: if they lose a level at every scheduled interval, doing nothing to hasten or slow the descent, it lasts roughly 400 days. Assuming they get lucky on a few rolls or keep to their purpose, they will probably stay active for 2 years on average. They'd have to go out of their way with epic accomplishments (killing a greater demon, murdering people in the streets to harken the Judges' law, building enormous works of art dedicated to Irem, etc) or be consuming relics themselves (a blasphemous act) to spend more time active.
Since the descent is on an exponential curve, they've already dropped down to Sekhem 6 after 8.5 days, and are due to drop to Sekhem 5 after 10 more days. Basically, if they've been recently awakened, but had some time to orient, plan, and start getting shit done, they're at Sekhem 6 or less. It goes pretty quick. If they've been around for a while, kicked their cult into motion, and are finalizing plans, have time to work on themselves, are preparing for their long-term plans.. their more likely to be at Sekhem 3 or less.
However, their cult can always raise them again, if they have access to adequate relics. Frequent or frivolous awakenings are highly discouraged (especially because they lose a dot in Memory every time they rise - if they aren't actively working on themselves every Descent, they quickly lose identity), but the cult can call them ~6 months or so, for another 2 year active period. So if you have a highly motivate mummy (who can stave off Memory loss), they might spend every 2/3 years active, but it's more likely for them to rise once every decade or more.

The Purpose their given on an arising tends to require discrete steps to complete. An on-going one like that doesn't really fit with how they work. They'd be more likely to be called to protect the Robe of the Dethroned Queen for a critical period of time, kill the people trying to get it, or reclaim it after its been taken. Essentially, they'd be woken up every time their cult discovers an enemy plot to take it, and return to slumber once that's dealt with.

Oookay, that's a lot faster than I anticipated. Still, it just means that their first contact will have to be the Cult itself (and its ghostly guardians). I still have some follow-up questions about the Descent, which I'll leave for the end of this post.

Hope that helps,
~Seraph Kitty

Immensely.

I will note that there is one other method wherein a Mummy could have been active for 35-40 years without ending their descent, and that would be if they were awake for a Sothic Turn. This probably isn't the best route to go down, one of the best ways to interact with a Mummy as an antagonist is to identify their Purpose and use that to mess with them indirectly or as leverage to cut deals, and a Sothic Rising means that the Arisen is awake with no purpose and stays at Sekhem 1 until something forces them to lose a Sekhem (death, blasphemy against their Judge, something like that) or they willingly end their descent. It would also mean your Arisen antagonist is likely hovering around the weakest end of the power scale, which probably makes for a less interesting encounter and would mean you wouldn't get to showcase the Descent through having the Mummy appear weaker from encounter to encounter.

I will note that there is one other method wherein a Mummy could have been active for 35-40 years without ending their descent, and that would be if they were awake for a Sothic Turn. This probably isn't the best route to go down, one of the best ways to interact with a Mummy as an antagonist is to identify their Purpose and use that to mess with them indirectly or as leverage to cut deals, and a Sothic Rising means that the Arisen is awake with no purpose and stays at Sekhem 1 until something forces them to lose a Sekhem (death, blasphemy against their Judge, something like that) or they willingly end their descent. It would also mean your Arisen antagonist is likely hovering around the weakest end of the power scale, which probably makes for a less interesting encounter and would mean you wouldn't get to showcase the Descent through having the Mummy appear weaker from encounter to encounter.

Oh, I'm aware of all of that. That's all really useful information if you're running Mummy, or interested in playing it. But for someone wanting to use an Arisen as an antagonist with a plan to mod the rules like the OP, that level of nitty gritty isn't necessary and also runs into the trap of misrepresenting the idea of the Mummy. If I want to highlight an NPC Arisen in a game, from a story perspective, you aren't going to capture the descent by having the Arisen be Sekhem 1/2 all the time save spiking to 7 when in their Tomb. That has a very different flavour to encountering an Arisen at Sekhem 10, then a few days later at Sekhem 7, then a week later at Sekhem 4, and so on. The former gives the impression of an undead creature bound to its resting place and granted phenomenal powers when inside, the latter allows you as a Storyteller to actually show the Descent to an external audience.

That was what encouraged me from changing the timeline and saying the Mummy will be awakened by its Cult - they'll consider the PCs' presence as a possible threat, and that false alarm will make the Mummy too weak to handle the return of the Dethroned Queen by itself.

As for the Descent itself, a few questions:
First, what happens when a Mummy wakes up? Eldritch flares? A corpse slowly regenerating itself? I need some help with the visuals.
Second, how does having high/low Memory work, exactly? I'm having some trouble grokking that part.
Third, I've read somewhere another way to bring a Mummy back from the dead is good old human sacrifice. Is it a possession type thing, where the Mummy's Sekhem takes over the new host, or does the old body reappear?

As an unrelated question, how many Affinities/Utterances does a Mummy get, out of chargen? Want to make sure it's not overwhelming, but needs to feel powerful.