My problem with palace of the dead is it has fallen into the same problem as diadem, it has some interesting ideas but they didn't add any variety to objectives, once again it's just kill all enemies and move on.

In ffxi each floor of nyzul isle had a different objective, like a puzzle where you had to activate lamps in a sequence, or kill a specific enemy or kill a mini boss or bonus objectives like avoid being spotted by certain enemies, there could also be notorious monsters on random floors and if you killed them they dropped a chest with a special weapon inside.

Stuff like this could easily have been used, like having a wanted target appear on random floors that 100% drops a blue chest. This is better than diadem but once again I think they missed an opportunity to make it better.