From a completely different direction:

I'd love to see Adepts from Unknown Armies get dropped into Mage. After all, their magic is firmly rooted into Post Modern ideas and is explicitly fueled by lowercase-P paradox. Making it fueled by uppercase-P Paradox as well would be... interesting.

On top of that, they're dark mirrors of Mages themselves - they're one-and-all addicted to their magic, having their magic, being their magic. It's what drives them to ruin their lives - when things like "being sober" and "telling the truth" are incompatible with...