Undead Biome/dimension

A Biome/Dimension that has been destroyed/cursed/claimed by the Nether or End. Mostly tougher undead roam this region and in villages it is just a prison for villagers who are now enslaved and trapped in cages. The world looks like the normal realm except everything looks more bitter and all the animals that spawn are zombie/skeleton like.

In this realm, have more creatures resemble werewolves or vampires (Not called, but share similar ability's and looks like a deformed villager).

If this was a dimension it'd be awesome if it was only accessible through a ruin that is at a depth that as deep or deeper then bedrock and is guarded by a boss/spawner or requires a artifact to open. 

I'm open to any ideas or suggestion. The goal is to have more undead, bosses, worlds, and curses/diseases