Conceptually, there are four levels of Annihilium. When someone dies (3 or so days after), the majority of their soul enters level 1. from here, they can be resurrected by holy magic or some god, or they can be temporarily recalled as shades. after some amount of time, they enter the second level. From here, they can only be "revived" by necromancers as powerful ghastly warriors or truly restored by the most powerful angels. Nearing the end, those in the third level can only be used by powerful necromancers. And finally, once something enters the fourth level, it is destroyed completely.