More Darwinian Struggle in the Underworld

They will not rest until their enemy is defeated utterly!

d12
1. Cabal of necromancers in need of constant supply of fresh corpses versus popular new cult with business ties to sepulcher builders guild, dedicated to elaborate funerary practises and secure interment for future resurrection event
2. Legitimate royal line of subterranean humanoids versus Subterranean Humanoids for a Democratic Society following failed purge
3. Cerebral puddings versus mindless yet strangely united slimes, oozes, and jellies for prime feeding grounds
4. Formal rivals of nearly forgotten pantheon versus upstart neo-godlings, evil high priests on both sides work overtime on conscription, mass bamboozlements, seizing loot for war chests
5. Subterranean humanoid adults versus their own children following declaration of independence by new generation born with next-wave evolutionary features including advanced enlightenment, blank stare, soulless eyes, astonishing viciousness
6. Levitating gold-eaters intruding from adjacent sphere versus tabulator giants (huge, musclebound, terrific at math but otherwise mentally negligible) with controlling interest in Underworld Mint
7. Colossal semi-intelligent naked cave buffalo versus giant talking sword beaked hummingbirds over animus incurred over the course of long symbiotic relationship
8. Private waste management firms of the subterranean humanoids versus one another for gigs
9. Trans-planar sentients' League of Beautification versus mutant humanoids' Union of Vandals
10. Cult of the Terror God versus itself in schism over interpretation of scripture, specifically proper cultivation of fear in day-to-day dealings with others
11. Giant cave crustaceans versus giant cave mollusks, just another outbreak of hostilities fueled by their eternal natural enmity
12. Evil wizard obsessed with monster ecology versus evil wizard obsessed with fiendish traps, puzzles, and riddles, minions/allies/dupes make proxy war on one another, invisible stalkers everywhere