Lunar Events

The Celestial Events are a series of four Hardmode, post-Plantera events initiated by defeating the Lunatic Cultist boss. Once the boss is defeated, several surface biomes show a large moon in their backgrounds, and spawn several unique enemies. The moon biomes will spawn in four distinctly spaced sections of the world. Defeating the pillar will revert the area back to normal. In order to defeat any of the four pillars, one must first kill 100 monsters (150 in Expert Mode) corresponding to the selected pillar in order to remove the barrier that is protecting it. To find where these pillars are, open your map. There will be icons of each pillar which will show where it is.

Each of the four variants has a different theme, along with a corresponding Celestial Tower variant that acts as the centerpiece of the event.

Upon defeating all four pillars, the message "Impending doom approaches..." appears in chat. The screen begins to shake, and approximately one minute later the Moon Lord will spawn on top of the player.

Tips

 * When fighting the Solar Pillar, take into account that the Crawltipede does not target players on the ground. Knowing this, you can easily defeat the pillar while staying on the ground.
 * The pillars retain their damage, regardless of player deaths.
 * An effective setup for melee players is The Horseman's Blade and Turtle Armor or above. Then build a small area where you can have lots of statues that spawn enemies so when your sword kills them, it spawns homing pumpkin heads. Have up to three statues of the same types.
 * An effective setup for a melee player could be the cosmic car key and vampire knives as it allows the player to dodge all monsters and also heal the player at a good rate.

History
Événements Lunaires