Lunatic Cultist

The Lunatic Cultist is a Hardmode, post-Golem boss summoned by killing all four Cultists that spawn at the Dungeon's entrance after Golem is defeated. Beating the Lunatic Cultist initiates the Lunar Events.

Behavior
The boss only has one defined stage, but its attacks become progressively stronger as it loses health. During the fight, it flies around at random, firing lightning, fireballs, shadowflames, exploding packed ice, and two volleys of five destructible stardust projectiles each.

It will often project illusory duplicates of itself, only one of which can be attacked to deplete the boss's health. These illusions are summoned one by one, and can be prevented by damaging the Cultist enough while summons them. The illusions are semi-transparent, which makes it easier to tell them apart.

Each time the player attempts to attack one of these illusions, the Lunatic Cultist summons a Phantasm Dragon, a Wyvern-like enemy, to attack the player. If the Phantasm Dragon is not defeated and the player attacks another duplicate, an Ancient Vision, which looks like the head of the Moon Lord, will be summoned.

to avoid the cultist summoning the phantasm dragon hit the original cultist not the copies

Tips

 * Avoid defeating the Lunatic Cultist if you are not yet ready for the Lunar Events, as after beating the Cultist the Lunar Events begin immediately, and there is no way to de-summon them (aside from defeating them).
 * Shooting the decoy cultist is not a bad idea if you have vampire knives. The Phantasm Dragon is very long and you can easily regain some life by hitting the Dragon with a wide barrage of knives.

Trivia

 * It appears visually similar and may be a nod to Crowno, an artist at Re-Logic, whose vanity set is often the subject of discussion and speculation by fans. It, as well as the Lunatic Cultist's graphics, resemble a plague doctor costume, which was a garment worn by physicians who treated the Black Plague in 14th century Europe.
 * It is the smallest boss, and the only boss without an awakening message.