End variants of mobs that already have Nether/fire/hell variants. Mo' Creatures doesn't naturally spawn anything in The End because it was never planned/never developed to do so. Also, NetherAPI?

[OnePlayer480]

So far, there are 6 mobs that have Nether/fire/hell variants (rat, wraith, ogre, manticore, scorpion, horse), so my suggestion is adding End variants of those same mobs. Something like [Endrat], [voidwraith], [voidogre], [voidmanticore], [voidscorpion], [horsemob end variant).

The other solution I thought could be that instead of creating a whole new void/end category, which involves developing new content, instead, the cave/dark variants seen in the overworld could be reused in the end, and the dimension is already naturally really dark all-around so having them spawn in the End is not too thematically odd, and these variants would naturally spawn in the end more often than in the overworld (assuming they would rarely spawn just like the dark manticore occasionally does in some biomes). So the only new mobs would be like a darkrat/voidrat?, darkwraith/voidwraith?, no need to do the other 4 I didn't mention because those already have dark/cave variants. This could also work as a temporary fix for farming more dark hearts (as currently there is technically no reliable way to farm them from tamed mobs due to unimplemented extra breeding ideas?/mechanics?), as the Nether already lets you gain Fire hearts easier than the overworld due to only spawning fiery mobs and naturally spawning the fire ogre often. And undead hearts aren't hard to come by in the overworld due to undead but still rotten and fleshy mobs being all-around the most common enemy type there.

The last thing I would suggest?, probably restricting spawning to only the vanilla END biomes (or biome) because recently there has been several End mods that have released or update frequently, and they tend to have this issue in which if a mod only needs the END tag to be active for it to attempt to spawn its mob(s), it will do so, which can lead to really weird scenarios like, say, for example, a dark manticore, a mob that spawns in biomes with flora in the overworld, spawning in a the acid biome from Stygian End, or a theoretical dark/end wrait spawning in a biome almost entirely filled with natural light sources.

The other alternative to this would be compatibility with NetherAPI as it already balances more or less well spawns from multiple Nether and End mods quite well so certain mobs spawn in biomes that suit them or just the vanilla end biome, to avoid issues, but that might be too much work so it is understandable if that is not a viable option from a development standpoint.