Dark Mage

The Dark Mage is a mini-boss that spawns in the Old One's Army event during wave 5 in Tier 1 and during waves 4 and 6 in Tier 3. It will freely float a bit above the ground. It randomly chooses between three attacks:
 * The Dark Mage summons Dark Energy.png dark energy, and hurls it directly at the player, dealing 80 / /  damage.
 * The Dark Mage summons a large rune, which then generates a large area of light that heals most NPCs in its 62.5-tile range (who have at least 30 maximum health, who deal at least 1 damage, and who are not a Dark Mage) by up to 500 health.
 * The Dark Mage begins chanting, and a Dark Sigil.png dark sigil will appear. After a short moment, Old One's Skeletons will appear from them. This attack cannot be done if there are more than 200 NPCs in the world.

Trivia

 * The pet drops from the Dark Mage in T1 are one of the highest drop chances for any pet items from enemies, beaten out only by the Bone Key from the Dungeon Guardian.
 * On the, the War Table, War Table Banner, Dragon Egg, and Gato Egg are not affected by Luck, unlike most uncommon loot drops. Thus, they will always drop at their listed drop rates.
 * Dark Mage can't heal itself, other Dark Mages and Moon Lord
 * If any boss has turned to another phase, and then Dark Mage heals them to full health, those bosses still maintain their current phase (with an exception like Santa-NK1, Plantera, King Slime, Queen Slime as it will convert into the first form after fully heal). Bosses like Golem, Brain of Cthulhu, Eater of World, Flying Dutchman will not heal to full HP since the next phase they already turn into a different entity, which already has full HP, or they have many different segments that already have been destroyed.