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. It says How do you know when summoned.

The boss only has one defined stage, but its attacks become progressively stronger as it loses health. During the fight, the boss will fly around seemingly at random, firing lightning, fireballs, shadowflames and exploding packed ice at the player. It also has the ability to fire five destructible stardust-like projectiles twice in a row. In addition, 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 if you can damage the Cultist enough while he's summoning them, he will stop. This makes it possible to prevent the spawning of any illusions, and thus prevents the fight from becoming a bullet hell. The illusions have a transparent appearance compared to the Lunatic himself, 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.

It is recommended to avoid defeating the Lunatic Cultist if you are unprepared for the Lunar Event and/or the Moon Lord, as after beating the Cultist the Lunar Event begins immediately, while defeating the event spawns the Moon Lord.

It is highly likely that when you defeat the Lunatic Cultist that you will end up over one of the Celestial Towers or near it when it spawns.

Trivia

 * Its lightning attack seems to be fired from a giant and immobile Magnet Sphere.
 * Its lightning attack also seems to be a reference to an attack used by Agahnim in The Legend of Zelda: A Link to the Past.
 * The packed ice it fires is similar to that of the Ice Queen.
 * It appears visually similar to a plague doctor, a kind of physician who treated the Black Plague in the fourteenth century C.E.
 * It also appears visually similar and may be a nod to Crowno's (developer) vanity set.
 * It is the smallest boss.
 * It is the only boss without an awakening message.
 * It is the only character in the game that speaks.