Boss Rush - Official Calamity Mod Wiki

The Boss Rush is a special event that is activated upon the use of Terminus. Although it can be summoned at any point in the game, it is recommended to be fought after all other bosses are defeated. During the event, every vanilla and Calamity boss spawns sequentially in a predetermined order. The bosses summoned have immensely buffed HP and damage and use modified AI, giving them all similar difficulties despite their usual distance in the game's progression. The Boss Rush can be deactivated at any time by using Terminus again.

Boss Rush - Calamity Mod Wiki

JUST DEFEATED CALAMITY DEATH MODE BOSS RUSH!!!! : r/CalamityMod

Boss Rush - Official Calamity Mod Wiki

Terraria Boss Rush, Funkipedia Mods Wiki

Music Boxes - Official Calamity Mod Wiki

Boss Rush - Calamity Mod Wiki

The ultimate boss rush : r/CalamityMod

I think the wiki may be a bit broken : r/CalamityMod

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