Palace of the dead lore?

[Cilia]

There really isn't any information on it in-game, other than (at least some of the top layers) are built on Gelmorran ruins and given how some dead NPCs can appear as rare spawn mobs it may be some kind of purgatory.

Little else is explained about it, but that's kind of what makes it so interesting and frightening.

There may be more information on it in Tactics Ogre (from which it and Nybeth both originated), but I don't know about that given my general disinterest in Matsuno's works.

[Jandor]

There really isn't any information on it in-game, other than (at least some of the top layers) are built on Gelmorran ruins and given how some dead NPCs can appear as rare spawn mobs it may be some kind of purgatory.

I assume the dead NPCs are a result of Nybeth's experiments. Would make sense that Edda wasn't his first attempt.