Brain of Cthulhu

Type	Flying Enemy
Environment	The Crimson
Damage	20 / 36 / 54 / 72 / 90
Max Life	100 / 170 / 187 / 216 / 238
Defense	10
KB Resist	20% / 28% / 36%
Immune to
Cold	Vulnerable
Water	-
Sickness	Vulnerable
Electricity	-
Heat	Vulnerable

Type	Boss
Environment	The Crimson
Damage	30 / 54 / 81 / 99 / 135
Max Life	1500 / 2550 / 3060 / 3251 / 3901
Defense	14 (21 while spinning)
KB Resist	50% / 55% / 60%
Immune to
Cold	Vulnerable
Water	-
Sickness	Vulnerable
Electricity	-
Heat	Vulnerable
Coins	5

Type	Boss
Environment	The Crimson
Damage	30 / 54 / 81 / 99 / 135
Max Life	1500 / 2550 / 3060 / 3251 / 3901
Defense	14
KB Resist	50% / 55% / 60%
Immune to
Cold	Vulnerable
Water	-
Sickness	Vulnerable
Electricity	-
Heat	Vulnerable
Coins	5

If you were looking for the Brain of Cthulhu on the vanilla wiki, click here.

"...A product of the folly of the Gods"

The Brain of Cthulhu is a Pre-Hardmode boss that is fought in The Crimson. It can be fought at anytime.

While in Revengeance and Death Mode, the Brain of Cthulhu has a buffed AI that is much stronger and more complex than the fight in Classic and Expert Modes.

Spawn

The Brain of Cthulhu does not spawn on its own and requires the player to either break 3 Crimson Hearts or use a Bloody Spine in the Crimson.

Behavior

In Revengeance Mode

The Brain of Cthulhu has two phases in Revengeance and Death Mode. This page will not be covering Classic or Expert Modes for the Brain of Cthulhu. If the Brain of Cthulhu is led outside of the Crimson, it will enrage, causing both the Brain and its Creepers to become much faster. It is less aggressive when fought in the Underground Crimson.

The Brain and the Creepers are capable of inflicting multiple debuffs upon contact damage.

Debuff	Duration	Chance (Brain)	Chance (Creepers)
Debuff	Poisoned	2.625 - 5.25 seconds	11/243	11/81
Darkness	1.5 - 3 seconds	11/243	11/81
Cursed	0.375 - 0.75 seconds	2/243	2/81
Bleeding	3.75 - 7.5 seconds	11/243	11/81
Confused	0.75 - 1.5 seconds	2/243	2/81
Slow	2.625 - 5.25 seconds	11/243	11/81
Weak	5.625 - 11.25 seconds	11/243	11/81
Silenced	0.75 - 1.5 seconds	11/243	11/81
Broken Armor	4.875 - 9.75 seconds	11/243	11/81

Phase 1

In the first phase of the fight, the Brain itself is invulnerable but will still have contact damage, there will be 25 Creepers that spawn alongside the brain, which must be killed to progress the fight. During this phase the Brain will teleport around the player at an increasing rate as Creepers are killed. It will also move towards the player after teleporting, getting faster the more Creepers are killed.

Unlike in lower difficulties, Creepers do not drop Crimtane Ores or Tissue Samples when killed.

Phase 2

Once the Brain's Creepers have all been killed, the Brain transitions into phase 2 and become vulnerable to damage.

During Phase 2, the Brain will continue to teleport around the player and move towards them at an increased speed. There will also be 3 mirror images around the player that will mimic the Brain's movement. They start somewhat transparent but become more opaque as the Brain loses health, making it harder to tell which is the real one.

At 30% health the Brain will switch to another attack, where it will fly around the player in a quick loop before dashing towards them before teleporting.

In Death Mode

Can teleport much closer to the player.
Creepers move faster.
Gains decreased attack delay as its health decreases.

During the Boss Rush

Max health increased to 1,000,000 / 1,700,000 / 2,720,000
Moves and teleports much faster the less Creepers there are remaining.
Movement speed and teleportation greatly increased and increases further at lower health.
Creepers movement speed and acceleration greatly increased.

Summons

Resistances

Creepers take reduced damage from most non-minion piercing projectiles. Each hit decreases the damage of the next hit by 12%, until the eighth hit onwards which deal 20% of original damage.
Creepers take 20% damage from grenade-type projectiles. A list of affected projectiles is below.

Resisted grenades
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Creepers take 50% damage from the Demon Scythe and true melee hits.

Aftermath

The Merchant will begin selling Healing Potions and Mana Potions.

Tips

For more elaborate strategies on defeating the Brain of Cthulhu, including weapon and arena recommendations, see Guide:Brain of Cthulhu strategies.

If being fought in the Underground Crimson, it is wise to place platforms in the center of a Crimson chasm as they are usually the largest area in the underground and will allow for more movement.
Piercing weapons are useful for the first phase as they will allow you to damage multiple Creepers at once.
Lighting up your arena will help alleviate some of the effect from the Darkness debuff.

History

edit

These history sections are still a work-in-progress, and may not yet contain changes relevant to the current version of the Calamity Mod.

2.0.4.002: Buffed contact damage in Master Mode from 135 to 162 , and Creeper's damage from 120 to 144 . Buffed blood shot damage from 108 to 114 .

2.0.4.001:
- Buffed health from 1500 / 2550 / 3060 / 3251 / 3901 to 1500 / 2550 / 4207 / 3251 / 5364 , and Creeper's health from 100 / 170 / 187 / 216 / 238 to 100 / 170 / 238 / 216 / 303 .
- Buffed contact damage from 30 / 54 / 81 / 99 / 135 to 36 / 54 / 81 / 108 / 135 , and Creeper's damage from 20 / 36 / 54 / 72 / 90 to 24 / 36 / 66 / 96 / 120 .
- Now turns the Calamity Boss Health Bar red when enraged outside of Revengeance Mode.
- No longer uses a global scaling contact damage formula based on boss velocity.
- Decreased Creeper amount from 25 / 30 to 20 / 30 , in the For the worthy seed from 40 to 35, and in Legendary Mode from 50 to 40.
- No longer deals contact damage during phase 1, and Creepers no longer deal contact damage while not charging in all difficulties.
- Creepers now take 25% damage from damaging debuffs.
- Revengeance Mode changes:
  - Decreased enrage scale boost while on the surface, and surface enrage no longer triggers when in front of unsafe Crimstone walls.
  - Increased teleport distance and maximum velocity in phase 1.
  - Creepers now teleport with the Brain when not charging, and have a telegraph when they're about to charge.
  - Increased Creeper velocity, and velocity scales with how many Creepers are alive, but velocity is now less affected by enrage scale.
  - Decreased the maximum time before Creepers return to the Brain, and Creepers now fire blood shots when returning.
  - Increased knockback resistance, and now creates 4 additional clones in the cardinal directions in phase 2.
  - Now starts performing spinning lunges at 80% health instead of 60%, and fires a spread of blood shots during spinning lunges.
  - Now has a smaller spin radius, and waits longer before teleporting after a spinning lunge.
  - Now fires blood shots from 2 directions when below 60% health, and from 4 directions when below 40% health.
  - Now lunges faster, has a smaller delay between spinning lunges, has increased blood shot velocity, and can teleport to the cardinal directions when below 25% health.
  - Now lunges even faster and has an even smaller delay between spinning lunges when below 10% health.
  - Increased minimum backup distance before performing a spinning lunge from 25 tiles to 40.
- Now has more knockback resistance at the start of phase 2, creates 8 more faint illusions, has an even smaller delay before the spinning lunge, lunges even faster, shoots more blood shots in a larger spread, blood shots have increased velocity, Creepers charge even faster based on how many are alive, and Creepers no longer push away from each other in Death Mode.
- Now spawns 30 Creepers, it and Creepers gain a small boost to enrage scale, Creepers have immunity to knockback and less inertia, charge more often, and can charge for longer, and moves faster in phase 1 in Master Mode.
- Now makes Creeper charges predictive, has a faster phase 2 move speed and less inertia, spawns additional Creepers during phase 2, shoots more blood shots in a wider spread, charges at the player longer after spinning lunges, and spinning lunges are predictive in Revengeance Master Mode.

2.0.3.008: No longer deals contact damage in phase 1 in Revengeance Mode.

2.0.3.003: Nerfed speed in phase 1 in the Get fixed boi seed.

2.0.3.001: Buffed health from 1400 / 2380 / 2856 / 3033 / 3639 to 1500 / 2550 / 3060 / 3251 / 3901 .

2.0.1.002: No longer hides its minimap icon below 20% / 100% health.

1.5.1.003:
- Enters phases faster in Revengeance Mode.
- Charges faster in Death Mode.
- Creepers now spread out more in Death Mode.

1.5.1.001:
- Buffed health from 1000 / 1700 / 2720 to 1400 / 2380 / 2856 .
- Increased distance the boss teleports away from the player while enraged.
- In Revengeance Mode, Creepers no longer drop Crimtane Ores or Tissue Samples. The treasure bag now contains an additional 100-180 Crimtane Ores and 60-120 Tissue Samples.
- It and its Creepers are now vulnerable to cold, sickness, and heat debuffs.
- Now drops Brain of Confusion regardless of world difficulty.

1.5.0.003:
- Creepers now take 50% damage from Demon Scythe projectiles.
- Creepers can now drop Hearts when killed in Revengeance Mode.

1.5.0.002: Fixed Creepers incorrectly using enraged AI while not on Malice Mode.

1.5.0.001: Nerfed Boss Rush health from 1,000,000 / 1,700,000 / 2,720,000 to 100,000 / 170,000 / 272,000 .

1.4.5.004:
- No longer despawns outside of the Crimson but instead enrages in Revengeance Mode.
- Now less aggressive when fought in the Underground Crimson in Revengeance Mode.
- Now transitions to phase 4 at 55% health instead of 50% and phase 5 at 40% health instead of 30% .
- Nerfed Creeper's speed in Revengeance Mode.

1.4.5.003:
- Now gains increased movement velocity and decreased attack delay as its health decreases in Death Mode.
- Creepers now have increased velocity in Death Mode.

1.4.5.001: Implemented a boss kill time for the Creepers of 30 seconds.

1.4.3.001:
- Nerfed contact damage from 30 / 54 / 67 / 77 to 30 / 54 / 64 / 71 .
- Nerfed final phase contact damage from 80 / 92 to 76 / 84 .
- Nerfed Creeper's damage from 20 / 40 / 50 / 57 to 20 / 40 / 50 / 56 .
- Nerfed blood geyser damage from 60 / 69 to 60 / 67 .
- Death Mode changes:
  - Transitions into Phase 3, 4, and 5 immediately instead of below 90%, 70%, and 50% health.
  - Hitting the boss has the least effect on delaying teleportation immediately, instead of gradually having less effect as health lowers.
  - Has 99.1% knockback resistance immediately, instead of having 58.6% knockback resistance and gradually taking less knockback as health lowers.
  - Moves at the highest speed immediately, instead of gradually speeding up as health lowers.
  - Decreased Creeper speed.
  - Decreased teleport frequency while Creepers are alive.

1.4.2.106:
- Buffed Boss Rush health from 200,000 to 1,000,000.
- Buffed Creeper's Boss Rush health from 20,000 to 100,000.

1.4.2.105:
- Reworked Revengeance Mode AI:
  - Buffed health modifier from 1.4x / 1.9x to 1.6x / 2.1x .
  - Will never teleport on top of the player during phase 1.
  - Can now deal damage in phase 1 again.
  - If there are 5 or fewer Creepers alive, all Creepers become immune to knockback.
  - Creepers now take 60% damage from non-minion piercing projectiles.
  - Moves faster and teleports more frequently in phase 1 based on how many Creepers are alive.
  - Creepers now charge as a swarm more frequently if there are less alive.
  - Will not despawn if fought in the Crimson.
  - No longer has a map icon at low health.

1.4.2.104:
- Nerfed health modifier from 1.6x / 2.3x to 1.4x / 1.9x
- Nerfed Creepers' health modifier from 1.2x / 1.4x to 1.1x / 1.2x .
- Can no longer hit the player in phase 1.

1.4.2.103:
- Revengeance Mode changes:
  - Buffed health modifier from 1.4x / 1.9x to 1.6x / 2.3x .
  - Creepers now have a health modifier of 1.2x / 1.4x .
  - Creepers no longer respawn.
  - Can no longer hit the player in phase 1.

1.4.2.001:
- Nerfed Boss Rush health from 400,000 to 200,000.
- Nerfed Creeper's Boss Rush health from 40,000 to 20,000.

1.4.1.001:
- Buffed Boss Rush health from 200,000 to 400,000.
- Buffed Creeper's Boss Rush health from 20,000 to 40,000.
- Buffed Boss Rush damage modifier from 3x to 4x.
- No longer deals extra contact damage in Death Mode.
- Can no longer hit the player while teleporting.
- Decreased the speed at which Creepers spawn in phase 2.

1.4.0.001: Reduced Creeper respawn rates.

1.3.4.101:
- Buffed health modifier from 1.25x / 1.75x to 1.4x / 1.9x .
- It and its Creepers no longer have 10% damage reduction.

1.3.4.001:
- Nerfed health modifier from 1.8x / 3.4x to 1.25x / 1.75x .
- Increased rate at which Creepers spawn.
- Now has a maximum of 15 Creepers at a time instead of 10.

1.2.4.101: Buffed Death Mode health modifier from 2x to 3.4x .

1.2.4.002:
- Buffed health modifier from 1.5x to 1.8x .
- Lowered knockback resistance.

1.2.3.005: Now gains a 1.25x damage modifier in Death Mode, and Creepers now spawn every 3rd / 1st time the boss teleports in Revengeance and Death Mode.

1.2.3.004: Now gains extra knockback resistance in Death Mode.

1.2.3.002: Now gains a 2x health modifier in Death Mode.

1.2.0.004: Increased speed in Revengeance Mode.

1.2.0.002: Creeper now inflicts Marked for Death for 2 seconds in Revengeance Mode.

1.2.0.001:
- Now gains a 1.5x health modifier in Revengeance Mode.
- Now has a 2% chance to drop Laudanum or Stress Pills in Revengeance Mode.
- Now inflicts Horror for 3 seconds in Revengeance Mode.
- Creeper now inflicts Horror for 1 second in Revengeance Mode.

1.1.7.801: The status message "Bloody cysts are erupting from the crimson's flesh..." now appears when defeated.

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Brain of Cthulhu

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