So, does this give the Beast the ability to manifest any kind of object by spending Satiety? Including Astral artefacts? That's hellishly powerful. It might be better to have each instance of the Merit bound to a particular object (e.g. a giant sword).
I have no particular problems with this, except for the lack of flavour text.
This might want a different name, for avoiding confusion, and I can't help but think that it might possibly be better represented by picking a location to which you gain a significant bonus to opening Primordial Pathways, rather than simply having it be a Burrow like between Chambers of the Lair.
Court of Nightmares
This is very nice, although I can't help but think that you might want to lower the level allowances nd exclude humans from the list (that could easily be simulated with the Staff of Retainer Merits).
I like the idea, but I think it might be better to have the prerequisite be 'Astral Kinship' and to clear up the description a little. Add a bit more explanation.
March of a Hundred Demons
Again, I love the idea. Love it. What I don't get is exactly what the Merit does. So, I'm presuming that the Merit requires some kind of ritual procession or something, led by the Beast, which lets all those who participate in it fill their entire supernatural 'fuel' reserve, while losing all but 1 Willpower? Why do they lose Willpower? This would seriously break the energy economy for supernaturals. You're a vampire and a friend of a Beast with this Merit? You don't need to go feed on people! Neither do Beasts need to install terror, Changelings leech off emotions, werewolves devour spirits and sup at Loci. No offence, but this needs work.