Mob Swapping

As you purify the Nether, you'll slowly attract new forms of fauna into the world. When a normal Nether mob tried to spawn in a location with a high enough purification level, the spawn will fail and be replaced with one from the Overworld.

These spawns respect the Nether's day/light cycle, meaning you will will get Overworld hostile mobs during the night and passive mobs during the day.

Required Purification Level

Mob	Purification Level
Magma Cube	500
Blaze	1,000
Zombified Piglin	1,000
Hoglin	1,500
Piglin Brute	2,000
Ghast	2,000
Wither Skeleton	2,000