To accomodate and concentrate spawns across the new four floors, standardize a lot of obscure and arbitrary inconsistencies between the sets, and introduce both some actual floor scaling and an OOD table.
Highlights:
* No more necrophages, phantoms, or mummies in any of the sets. Still lots of other chaff, but these three didn't even have much thematic placement or bands to them.
* All hells now have soul eaters, slim chances for liches and even slimmer chances for at least one classed vampire. There's also a very slim chance in all sets (rather than just two of them) to place the 1 of the other paired hell between Dis/Geh and Tar/Coc.
* Zombies, skeletons, 5s, and 4s are less overwhelmingly common in all
hells. Reapers, select elemental representatives, soul eaters, and
stronger undead are a fair bit more common, especially hell knights
in Gehenna and blizzard demons in Cocytus.
* Tartarus now has a fair deal of hellwings (to correspond with the other demons in the other hells), a few revenants and jiangshi, a larger load of soul eaters, and a good deal more hellions / tormentors / shadow demons than before.
* A general shuffling of undead and lower-tier demons to make some spawn more or less per-Hell, which should help marginally distinguish the sets further beyond their most common demons / elemental representatives.
The Vestibule also has some adjustments- more cross-Hells representation, a handful of actual undead, and less 2s mostly unique to Pan. It's a slight loss of the chance to see lorocyprocas / cacodemons / green deaths in a three-rune game (...doing Vestibule for experience), but seperating the two demon hordesis just as important. Altogether, this should strengthen the identity of the Hells in their floor sets- undead + demons + elements doesn't have to solely mean a unique enemy per-branch, tons of derived undead and weakling demons, plus a branch end full of 1s.