Skeletor

The Skeletor is a strong Skeleton which spawns in the Catacombs from 3 dead Skeletons dropping their skulls in a 3-block radius. It drops Skeletor Armor

Spawning
The Skeletor spawns in the Catacombs on Floor III and above. It is spawned when 3 Skeleton-type mobs die and drop their skulls within a 3-block radius. When its spawning conditions are met, an animation will play showing the 3 skulls merging and the Skeletor will spawn.

Behavior
The Skeletor is hostile to all players. It will target the nearest player and run towards them at speed. It first throws its bone at players, similar to that of a Crypt Lurker, and then rushes in to melee at players holding a bone. Both the ranged and melee attacks deal heavy.

Trivia

 * Killing a Skeletor while its bone is in mid-flight will neutralize the bone, causing the player to take no damage from it.
 * The Skeletor is possibly named after Skeletor, the main antagonist of the Masters of the Universe series.