Lunatic Cultist

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

Behavior
The Lunatic Cultist makes its first brief appearance at the Mysterious Tablet as soon as the Cultists are defeated. It is not vulnerable to attacks at this time. It then warps to a new location in midair and summons one of three attacks:


 * A burst of three homing fireballs that explode on impact
 * An ice ball that fires ice shards in six directions as it flies
 * An orb that fires bolts of lightning

As the Lunatic Cultist becomes damaged, it adds two spreads of five destructible Ancient Light projectiles as part of his previous cycle.

In Expert Mode, it may also spawn numerous Ancient Dooms that fire four purple projectiles In a Plus sign after a while.

The Lunatic Cultist cycles through its various attacks, performing four to five of them before proceeding to spawn phantom duplicates of itself via a "ritual". Unless the one true Lunatic Cultist is interrupted by an attack from a player during this ritual, the duplicates fly in formation and add their homing shadowflame attacks.

Attacking a duplicate results in the summoning of the Wyvern-like Phantasm Dragon. If there is already a Phantasm Dragon inbound, attacking a duplicate triggers an Ancient Vision, which resembles a miniature Moon Lord head. Duplicates can be eliminated by interrupting the ritual again with player attacks, but if not, large quantity of duplicates can amass.

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). Take care that any minions/NPC's in the area don't kill the Cultist inadvertently.
 * If you have beaten the Martian Madness event, and have access to the Cosmic Car Key, it is very easy to dodge most of the Lunatic Cultist's Attacks. It is generally possible to complete the fight without going below 300 HP, if you do not fight the Phantasm Dragon.
 * One way to determine which cultist is real is by playing at night. The real cultist does not emit light like the decoys, so it will be very easy to determine the correct one to attack. And only the real cultist has a health meter.
 * Attacking 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 is a common belief that the Cultists' design was inspired by Crowno's clothes. However, according to Crowno, the Cultists were designed before it.
 * The boss' appearance resembles 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 one without an awakening message.
 * The Lunatic Cultist's mask and trophy are named "Ancient Cultist" rather than "Lunatic Cultist", as they are still using an early development name. Several other enemy drops from 1.3 also retained their early development names until later patches.
 * If Skeletron isn't defeated in a world but Plantera and Golem are, then it is possible that the cultists won't spawn making it impossible to spawn the lunatic cultist until Skeletron is defeated.
 * The Lunatic Cultist has an Expert Mode Treasure Bag in Terraria's game files, but it is currently unobtainable as he does not actually drop it.
 * If you wear the Ancient cultist mask and the lunar robe you can actually look like the lunatic cultist.