Board Thread:Lore Discussion/@comment-71.226.242.68-20131113201112/@comment-74.215.10.147-20151021073044

I would say that killing a Daedric Prince on their home realm would kill them, due to their essence having nowhere to go. The problem is actually having sufficient power and skill to do such a thing. Nothing short of another prince would have the such power to do that, and even then you'd need multiples, as in their home, the one being attacked would be more powerful, and the ones visiting would be less powerful, being in a foreign land would decrease their power a lot. So it's not a question of if they could be killed, it's a question of whether or not everyone would cooperate and coordinate well enough to kill them.

Tl;dr: They can be killed, but you better have a pretty big and powerful army.