At level twenty, Necromancer trainers* offer a group quest called The Art of Death. This quest requires you to travel to a level 20ish dungeon in north eastern Qalia, and do a very easy (aside from getting there) task for a master necromancer, convincing him to teach you the spell Rest of the Dead, which allows you to feign death. If you plan to do this quest immediately (at level 20), you will want a decently sized group, as the enemies in the coven are around level 20, and 3-4 challenge dots. They pull in groups of 2-3 at this level. If you're feeling brave, you can also get someone to cast invisibility on you, or use an invisibility carving, and just try to run through.