wither skeleton necromancer

A brilliant idea of designing a boss surpassing Minecraft freedom limitation(like building), is a wither skeleton necromancer with has unique features:

1. He summons wither skeletons rising from the ground, which means the player can’t dig a hole and hide, a wither skeleton will spawn on the block he at, making it an intense battle.
2. If the player damages this boss too much, it will turn to bones and resummon itself in other place.
3. To make fight more tricky, this boss should have its own structure sharpening its mechanics.
4. This skeleton boss may ride a wither skeleton horse(which walks regularly on soul sand).
5. This boss reward, is a wither upgrade for tools(wither damage) and armor(wither immunity) parallel to netherite.

This boss and structure will be find in soul sand valley or a “withery” variant of that biome where some fossils blocks will spawn as wither bone blocks and ranged wither skeletons will spawn, this structure may also respawn in warped forest or basalt deltas.