Ideas thus far:
Knights of Nirvana are ex-paladins and ex-blackguards that have been consumed by the all-encompassing law of Mechanus. While their power grows ever-greater, spurred on by the clockwork march of eternity, their souls slowly wither and die within them.
The Children of the Mausoleum are considered heretics, evil-doers, and worse. Hunted for espousing the belief that undeath is a natural state, the Children study the dark forces that draw back life from beyond the grave while trying to carve out a niche in the world for both themselves and their rotting wards.