What makes a Wither Skeleton spawn?
What conditions are necessary for a Wither Skeleton to spawn naturally, and can I manipulate those conditions to increase the chance of them spawning?
I want to make a Wither Skeleton spawning pad in the Nether but I'm having trouble finding Wither Skeletons. I've only heard that they spawn in Nether Fortresses.
They naturally spawn in Nether Fortresses, light level 7 or less where their lower half will be.
To increase the chances of one spawning, make sure the light level condition is met, and fill any holes in the floor. It doesn't matter about material, wither skeletons will spawn whether there is nether brick or not.
In nether fortresses, skeleton eggs/spawners will spawn Wither skeletons 80% of the time.