Events

Events (some also known as Invasions) are short-term occasions where varieties of special enemies spawn, most at elevated spawn rates, even near NPCs without needing to use a water candle, and attack players. Some events can occur randomly during gameplay, while others can be triggered via certain summoning items or special circumstances. Events spawn their own unique enemies during ordinary gameplay, which can, in turn, drop unique items that are only obtainable within the event. Some events also bring unique visuals and a unique atmosphere, such as an altered Moon and noticeable shaders applied to the screen. Events also are accompanied by their own special music, adding on to their theme. Depending on the particular event, they may last until a certain time limit is reached, or until a certain number of enemies are defeated.
On all versions, a progress bar can be seen in the bottom right corner of the screen to indicate how far the player has gone into the event, and how far they are from completing it. It only appears during invasion-style events (Goblin Army, (only if 75/150 slimes are defeated), , Frost Legion, Pirate Invasion, Pumpkin Moon, Frost Moon, and ) and will not appear during events that are time-limited (Blood Moon, Rain, (only if less than 75/150 slimes are killed), , and Solar Eclipse).
Note that certain invasions (Goblin Army, Frost Legion, Pirate Invasion, and ) have location requirements. The player must be no deeper than 67.5 tiles below the surface, and the player must be within 187.5 tiles horizontally of the location of the invasion. If the invasion has reached the center of the world, then the horizontal check can also be satisfied by the player being within 187.5 tiles horizontally of any town NPC, although at a reduced spawn rate. The town NPC's vertical position is not checked and so they can be housed far above or below your arena. 
There are currently 19 / 14 / 8 different events and invasions.
The , created to celebrate Terraria's 5th birthday, and the are the only events that do not spawn unique enemies nor play special music.
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== Peaceful ==
== Weather ==
==Pre-Hardmode==
== Hardmode ==
== Achievements ==
== History ==