Would be cool to reuse the
Aetherscope and make that the deep dungeon.
We would dig deeper and encounter more lost souls and the "X0" floor boss can be the spirit of a previous enemy/NPC we have encountered, can be a friend testing our strength or a foe out for revenge. can be like we are finally putting the souls to rest. Throughout the floors we can be aided by the souls of comrades and the special polymanders can summon the souls of our lost friends while the normal ones can stay the same but add a few different effects such as one that enacts that same buff we get fighting Zenos at the end of MSQ a regen/raise that lasts the current 10 floors but you can only ever carry 1.
just some ideas