Minecraft Dungeons:Necromancer

Necromancers, also known as Summoners, are undead hostile mobs found in Minecraft Dungeons that can summon undead mobs. They look similar to the Nameless One but are slightly shorter, and wear a black robe with blue markings.

Spawning
In Default difficulty, the Necromancer can only be found in Desert Temple and the Lower Temple. In Adventure difficulty, it can be found in the Cacti Canyon and in Apocalypse difficulty, it can be found within the Creeper Woods and the Creepy Crypt.

Appearance
The Necromancer is a large skeleton that wears blue turfs, a cape with blue stripes near the end, a golden belt with a blue gem in the middle, has greenish eyes, and wears a gold crown-like headwear. Necromancers always hold staffs with a blue orb placed upon a stick.

Behavior
Necromancers use their staff to summon undead mobs such as zombies and skeletons to attack players. After summoning, they'll flee and keep distance from the player, and then summon mobs again. Necromancers also can rapidly fire damaging bolts or beams from their staff to players.

Trivia

 * Internally, the Necromancer is known as the Summoner