Hmm? Ah, another contender. Very well, may the ritual commence!
— Boss Rush initiation message
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 (excluding the Exo Mechs, Adult Eidolon Wyrm, Queen Slime, Empress of Light, and Deerclops) spawns sequentially in a predetermined order. The bosses summoned have immensely buffed HP and damage and use modified Malice Mode 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.
Defeating the Boss Rush rewards the player with the Rock.
Upon starting the Boss Rush, bosses will spawn in a predetermined order that never changes. Only one boss will spawn at a time; the next boss will spawn once the prior boss is defeated. A total of 40 bosses will spawn during the Boss Rush. The bosses are divided into five Tiers, with each new Tier signified by a status message in the chat and a brief rest period.
If a boss cannot be summoned due to an improper time, the time will be changed to accomodate the boss.
The order is as follows:
|Brain of Cthulhu|
|Eye of Cthulhu||Sets the time to night (7:30 PM)|
|Skeletron Prime||Sets the time to night (7:30 PM)|
|Golem||Sets the time to day (4:30 AM)|
|Profaned Guardians||Sets the time to day (4:30 AM)|
|Eater of Worlds|
|Astrum Aureus||Sets the time to night (7:30 PM)|
|The Destroyer||Sets the time to night (7:30 PM)|
|The Twins||Sets the time to night (7:30 PM)|
|The Dragonfolly||Sets the time to day (4:30 AM)|
|Wall of Flesh||Teleports the player to The Underworld|
|The Hive Mind||Teleports the player to their spawn point|
|Skeletron||Sets the time to night (7:30 PM)|
|Storm Weaver||Sets the time to day (4:30 AM)|
|Signus, Envoy of the Devourer|
|Astrum Deus||Sets the time to night (7:30 PM)|
|Polterghast||Sets the time to day (4:30 AM)|
|The Plaguebringer Goliath|
|Calamitas||Sets the time to night (7:30 PM)|
|Leviathan and Anahita||Sets the time to day (4:30 AM)|
|The Old Duke|
|The Slime God|
|Providence, the Profaned Goddess||Sets the time to day (4:30 AM)|
|Jungle Dragon, Yharon||Sets the time to day (4:30 AM)|
|The Devourer of Gods|
Boss Rush Curses
There are three curses that can be enabled through the configuration options. They are disabled by default. The curses impose restrictions on the player while the Boss Rush is active. They serve no purpose other than to challenge the player and offer no additional rewards.
- The Health curse negates all positive life regen.
- The Dash curse disables all dashes from items such as the Ornate Shield, Statis' Ninja Belt or Shield of Cthulhu.
- The Immunity curse prevents the player from getting hit more than once within the span of three seconds. If the player is hit more than once within a span of three seconds, they will instantly die.
- Any effects that change the color of the background will be overridden by the custom background for the event. This includes those for day/night.
- Several bosses are sped up due to the potential speed of the player.
- Despite time being reset to the start of day/night for bosses that can only be fought at day/night, it is still possible to run out of time. In this case, the boss will despawn, time will reset back to day/night and boss will be resummoned with full health.
- All damage taken is increased (where applicable) to a minimum value that increases as the player progresses through the event:
- King Slime can spawn Rainbow Slimes and Umbrella Slimes when damaged, even without raining.
- The Eater of Worlds will be immune to all debuffs except Enraged, Kami Flu, and Shellfish Claps, and will take 99.9% less damage for ten seconds after being summoned.
- Golem's head will be immune to damage once detached from its body.
- The Profaned Guardians and Providence do not become invulnerable outside their respective biomes.
- Ceaseless Void currently does not spawn Dark Energies due to an oversight.
- Ravager's head does not spawn. It is unknown if this is an oversight.
- Despite the rest of the Boss Rush being based off of Malice Mode, Providence does not enter her nighttime form during the event. However, she can perform both the Crystal and the Holy Ray attacks regardless of the biome she was spawned in.
- Supreme Calamitas will not vanish upon reaching 1% HP like in her regular battle. Instead, the player will be prompted to finish her off after a delay.
- No matter whether she has been defeated in the world or not, she will always appear in her hooded form.
- Yharon does not spawn the flare bomb ring when defeated.
- Providence and the Wall of Flesh do not create Profaned Rock and Demonite/Crimtane brick squares when defeated.
- The waiting time between the prior boss's death and the next boss spawning is 1 second during Tiers 1 through 3, which is increased to 6 seconds during Tiers 4 and 5.
- All wire-activated mechanisms are disabled during a Boss Rush.
- Some of the bosses, such as Jungle Dragon, Yharon and Supreme Calamitas, are made easier in the Boss Rush compared to their usual fights.
- Supreme Calamitas' usual dialogues will not appear during the Boss Rush.
- Supreme Calamitas' Town NPC form will not disappear during the Boss Rush when she is summoned, unlike her regular fight.
- The health of the bosses during the event only scales up with 2 people in multiplayer.
- Defeating a boss that wasn't defeated prior to the Boss Rush will bring that boss' aftermath and will count that boss as being defeated outside of Boss Rush. The boss will also drop all of its normal loot as if it was defeated normally.
- Killing any creature during this event makes the background eye sigil glow red for a brief moment.
- Any critter, enemy, or boss (excluding Town NPCs) that spawned prior to activating the Boss Rush will immediately despawn.
- Many health and buff potions, as well as mana for mages should be brought, as the Boss Rush can easily take over twenty minutes.
- Auric Tesla armor is a good choice as it provides a wide array of set bonuses and regenerative effects.
- Despite being able to begin the Boss Rush at almost any point in the game, the player should definitely have end-game weapons and equipment before facing it if they hope to succeed.
- Contact damage with any of the bosses and their projectiles/minions should be avoided as they can easily deal over 200 damage even with endgame armor.
- Players should attempt to distance themselves from any floors or other solid tiles after defeating Providence, in order to maximize the amount of space available to them once Supreme Calamitas spawns and her arena generates.
- Although the identity of the messages' speaker and the background symbol are never confirmed in-game, they can be deduced as being an entity named "Xeroc" through hints and implications in various areas.
- In the lore, Xeroc is a mysterious godly figure and is implied to be the most powerful entity in Calamity's story. It is also the entity responsible for Blood Moons, hence the name of the Xerocodile item.
- Terminus features the same sigil design that appears in the background of the Boss Rush, and the Boss Rush's progress icon. In the original concept art for Terminus, the sigil is designed to represent various aspects of Xeroc, including its "gaze".
- The sigil in the background is internally referred to as "XerocEye".
- The Rock, rewarded upon beating the Boss Rush, mentions Xeroc in its tooltip.
- The boss progression was based on a series of polls that took place in the Calamity Mod Discord server, gauging players' favorite bosses and the ones they found the most difficult, with the resulting total being used to determine the rush's order.
- The Boss Rush Curses were inspired by the Pantheon Bindings from the game Hollow Knight. These Bindings, activated during the boss rush mode in said game, hindered the player character in various ways.
- "Hmm? Ah, another contender. Very well, may the ritual commence!" (when started)
- "Hmm? Oh, you're still alive. Unexpected, but don't get complacent just yet." (before entering Tier 2)
- "Hmm? Persistent aren't you? Perhaps you have some hope of prosperity, unlike past challengers." (before entering Tier 3)
- "Hmm? Your perseverance is truly a trait to behold. You've come further than even the demigods in a short time." (before entering Tier 4)
- "May your skills remain sharp for the last challenges." (upon entering Tier 4)
- "Hmm? So you've made it to the final tier, a remarkable feat enviable by even the mightiest of the gods." (before entering Tier 5)
- "Go forth and conquer 'til the ritual's end!" (upon entering Tier 5)
- "Hmm? You expected a reward beyond this mere pebble? Patience, the true reward will come apparent in time..." (after completing the Boss Rush)
|Combat||Damage Reduction • Defense damage • Enchantment • Hit Sounds • Immunity frames • Lifesteal • Minions • Proficiency • Rogue|
|Environment||Biome backgrounds • Events • Music • Status messages|
|Events||Acid Rain • Boss Rush|
|Items||Alternative crafting ingredients • Charge • Consumable • Crafting stations (By Hand) • Drops • Modifiers • Rarity • Recipes • Vanilla item recipes|
|Game||Bestiary • Boss Health Bar • Configuration options • Difficulty Modes (Death Mode • Revengeance Mode) • Fishing • Game controls • Lore • Speedrun Timer • Vanilla changes|
|Player||Adrenaline Meter • Aggro • Buffs and Debuffs • Death prevention • Defense • Rage Meter|