Brain Rot first appeared as Turned, an Alternate Ammo Type/Ammo Mod in Call of Duty: Black Ops III. It gives the weapon a capability of turning upwards of three Zombies by a singular player.
The Turned effect is indicated by the hit marker changing to that of two green eyes, killing a small amount of zombies around the affected zombie to die with the affected zombie themselves gaining the nameplate of "Turned", producing a green gas and having their eyes changing to a green glow. Turned Zombies will attack any standard zombies nearby for up to 20 seconds before dying. Turned Zombies also will one hit kill any standard zombie, regardless of the round but will ignore some unique enemies such as the Parasites along with completely ignoring any sort of boss.
Turned itself has a similar, long cooldown to that of Blast Furnace and Fire Works and Turned Zombies themselves are not immune to other Pack-a-Punch upgrades affects, but are immune to the damage of it, similar to that of player operated Traps. Turned Zombies will also be ignored by round progression, allowing the rounds to roll into the next one whilst Turned are still active.
Call of Duty: Black Ops 4
Brain Rot has a chance to be applied to an upgraded weapon when placed in the Pack-A-Punch Machine again. Accessing an Alternate Ammo-Type costs 2,500 points initially, which will give a random AAT alongside a damage boost, this can be done 4 times before the cost is lowered to 1,500 and will only re-roll the ammo-type.
Brain Rot ammo has a chance to infect an enemy zombie and have them become the player's ally for about 10 seconds. When affected with Brain Rot, a zombie will display the words "Brain Rot" above its head and furiously hunt down regular zombies, instantly killing them. Even Zombie Tigers can become infected by Brain Rot, which can take down Marauders and Destroyers with a single lunge attack. After the 10 seconds, the affected zombie will explode, killing all other zombies around it. The kills obtained from this method count as Headshot kills, allowing one to earn points, XP, and performance camo progress at a faster rate. Brain Rot ammo is super effective against Fire Catalyst zombies, causing them to explode in a high-velocity blast.
Call of Duty: Black Ops Cold War
Bullets deal toxic damage. Each bullet has a chance to turn a normal enemy to an ally for 15 seconds before dying (40 second cooldown).In-game description
Brain Rot can be added to any weapon, independently of its upgrade level for 2000 essence at the Pack-a-Punch machine. However, it will never activate on attacks dealing more damage than the target's health, making it less desirable on some weapon (the Knife, for example) and unusable during Insta-Kill.
Brain Rot functions similarly to past games. Every Brain Rot ammo has a chance to infect an enemy zombie that will attack other zombies for 15 seconds (20 with the Tier II upgrade) before entering a 40 second cooldown. After that delay, the zombie will either die or explode and deal toxic damage (if the ammo mod is upgraded to at least Tier I). The turned zombie will see its health bar becoming green and the mention "Brain Rot" next to it. Unlike its Black Ops 4 counterpart, the kills obtained from Brain Rot do not count as critical kills and only give 50 essence each.
Brain Rot can activate on all zombie types, excluding Elite and Boss class Zombies with Special class enemies such as the Mangler requiring the purchase of the Tier IV upgrade before they can be turned. While under the affects of Brain Rot, Special class infected will retain their abilities but will preference to melee enemies.
Weapons modded with Brain Rot will deal an additional 2x damage multiplier to Mimics and Tempests.
Like all Ammo Mods in Zombies, Brain Rot can be upgraded using Aetherium Crystals.
Tier I - Turned enemy explodes on death dealing toxic damage.
Tier II - Increased turned duration to 20 seconds.
Tier III - Turned enemy damage is doubled.
Tier IV - Special enemies can be turned.
Tier V - On turned enemy death, the turned enemy explosion turns 3 nearby enemies (30 second cooldown).
Brain Rot returns in Call of Duty: Modern Warfare III, functioning like its counterpart from Black Ops Cold War, but without the tier system.
Call of Duty: Black Ops 6
Bullets deal toxic damage. Each bullet has a chance to temporarily turn a normal or special enemy into an ally.In-game description
Brain Rot returns in Call of Duty: Black Ops 6 functioning similarly to the previous games where it can be purchased for Salvage at the Arsenal Machine.
Any weapon equipped with Brain Rot will receive a 1.5x damage multiplier against Abominations and Shock Mimics. This multiplier is increased to 1.75x if the player has Elemental Pop with the Vulnera Bean Minor Augment equipped.
Like all Ammo Mods in Zombies, Brain Rot can be imbued with two out of six possible Augments. Players can equip one Major Augment and one Minor Augment at a time.
Major Augment
Plague: The charmed enemy has a chance to turn other enemies.
Pheromone: The charmed enemy distracts nearby normal and special enemies for a short time.
Big Game: Brain Rot can charm elite enemies.
Minor Augment
Extension: Brain Rot duration is slightly increased.
Haste: Brain Rot cooldown is slightly reduced.
Explosive: Charmed enemies explode at the end of Brain Rot's duration, dealing toxic damage.
Call of Duty: Black Ops 7
Bullets deal Toxic damage. Each bullet has a chance to temporarily turn a Normal or Special Enemy into an ally.In-game description
Brain Rot returns in Call of Duty: Black Ops 7 functioning similarly to the previous games where it can be purchased for Salvage at the Arsenal Machine.
Now, Brain-rotted zombies will avoid slaying the last hostile zombie in the Round.
Like all Ammo Mods in Zombies, Brain Rot can be imbued with two out of eight possible Augments. Players can equip one Major Augment and one Minor Augment at a time. An extra Minor Augment can be imbued after unlocking all Augments.
Major Augment
Plague: Charmed enemy have a chance to turn other enemies.
Pheromone: The charmed enemy distracts nearby Normal and Special Enemies for a short time.
Big Game: Brain Rot can charm Elite Enemies.
Caustic Fumes: Charmed enemies deal Toxic damage to nearby enemies.
Minor Augment
Extension: Brain Rot's charm duration is increased.
Haste: Brain Rot's cooldown is reduced.
Explosive: Charmed enemies explode at the end of Brain Rot's duration, dealing Toxic damage.
Super Serum: Increase the damage dealt by charmed enemies.
Gallery
Call of Duty: Black Ops III
An example of a Turned zombie. Note the green glowing eyes.
A Turned zombie attacking a hostile zombie.
Call of Duty: Black Ops 4
An example of a zombie affected by Brain Rot. Note the green-hue in the eyes and the green smog around the zombie.
Call of Duty: Black Ops Cold War
Zombie being affected by Brain Rot. The Brain Rot icon within the Pack-a-Punch Machine menu.
Brain Rot in the Create-A-Class menu. The Icon showing Brain Rot is equipped on a weapon.
Call of Duty: Modern Warfare III
Brain Rot Acquisition Background Menu.
The Icon showing Brain Rot is equipped on a weapon.
Trivia
Call of Duty: Black Ops Cold War
It is possible to pet a turned Plaguehound or Hellhound by standing close to it and interacting with it which gives 50 point on the first execution.[1]
