Just a suggestion on adding PvP into palace of the dead, just make it like a dark souls system of invading another parties dungeon perhaps only 30-50 floors.
Invader would be solo but gives a slight boost to monsters hp and damage around them, 1v4.
Pomanders that negate a player invasion for the floor.
Players surviving from invader get a potshard, and player kills from invader gets them a potshard per kill ( or a new currency they can add with its own reward system)
replace invaders name with "_________ adventurer" having the prefix change with how many kills the invader has gotten. Obviously the invader cant be attacked by monsters so they would have to use them to their advantage.

Would always have to be 1v4 invader can only invade full parties alone, queue would be in a different area perhaps by a npc of the cultists Lambs of Dalamud.