Minecraft wiki entry for Nether_survival, associated text: The terrain is much harsher to navigate than in the Overworld: one false step could mean death by fiery lava. Nether fortresses and bastion remnants both spawn in the Nether. Nether fortresses are the homes of wither skeletons and blazes, and piglin brutes, piglins, and hoglins all spawn in bastion remnants.