Minecraft Dungeons:Skeleton Horseman

A Skeleton Horseman is an undead mini boss that spawns randomly in various levels $$.

Spawning
Skeleton Horsemen usually spawn on Adventure mode and above, and spawns randomly in groups in the Creeper Woods, the Soggy Swamp, the Pumpkin Pastures, the Cacti Canyon, the Desert Temple, the Dingy Jungle and the Overgrown Temple. In Apocalypse difficulty, they also spawn in the Redstone Mines, Highblock Halls and the Fiery Forge. They can also be found early on Default Mode uncommonly in the Cacti Canyon.

Behavior
Whenever a player approaches a newly-spawned Skeleton Horseman, it transforms into the Four Skeleton Horsemen and starts charging at the player. The Skeleton Horsemen also have high hit points and require constant damage to be defeated. They sometimes shoot at the player with a Longbow, dealing extreme damage.

Trivia

 * Rarely during Ancient Hunts, a single or less than 4 skeleton horsemen can spawn. They are also seen without a boss health bar.