CP2 Wiki
Boss - Brain Bug
Brain Bug.jpg

Biological - Psionic - Heroic

Offensive Stats
Damage 20
vs. Structure 40
vs. Heroic 30
Range 9
Weapon Speed 0.5
Defensive Stats
Armor 15
Move Speed 1.3
Complete Map.png


The Brain Bug is a giant Infestor boss. It has no weapons, but emits an aura of Toxic Gas that deals heavy damage over time and slow to nearby enemies. Once it is awakened it starts slowly creeping around the map leaving Eggs, Creep Tumors, and Spine and Spore Crawlers. Its movement is somewhat unpredictable, as it does not attempt to deliberately attack CP forces, but it does try to avoid taking direct damage from enemies. Unusually, it is typed Biological - Psionic - Heroic, and not Massive, making Big Game Hunter Mastery ineffective against it. However, you will get a BGH experience bonus from killing the Brain Bug.

The Brain Bug is located at the top middle of the map and is awakened when damage is dealt to it. This is useful as the player can choose when and how to engage in battle with it. Because of the radius of Toxic Gas engaging it in direct combat may prove difficult. It's important to focus it as a team or he will ravage around your base for long time.

The Eggs left behind by the Brain Bug can hatch into a range of minor EC units. When the Brain Bug dies, all active eggs it left behind also die. What is much more threatening is that to the north-east of the Brain Bug's spawn point is a hive cluster containing an Ultralisk Den spawning Primal Ultralisks, while one of the Hives spawns Larvae that transform into eggs that hatch Noxious Ultralisks. These Ultralisks are much more dangerous than the Brain Bug itself.

Many strategies for defeating the Brain Bug involve not triggering the bug, dropping Tac Nukes on the Ultralisk Dens in the top-center Lair-Hive cluster, and only engaging the Bug once the Dens are destroyed. This will likely take several nukes and significant caution, as the top-center Hive cluster also has three Brutalisks patrolling its perimeter.

Combat Strategies[]


If you have Ranger Mastery you can attack the Brain Bug from near the edge of Toxic Gas's range. Otherwise, staying in range to do damage may be difficult because of the slow. Stimpack will help with this but unless you have Iron Man Mastery staying in range while chasing will be difficult. Psionic Storm or in rare cases Psionic Warrior Mastery can be used for extra damage to the Bug itself, because of its Psionic type.

Tankz tactic[]

Go in from the backdoor and start nuking the ultra spawners, you'll need either 2 of the CD reduction talent on nuke. or 1 of those + double nukes to do so. Chain nukes together till you kill both spawners.

Now, engage brainbug and do as much damage to him as possible while you follow him out. once you get low on HP, leave his posion and chain grenades + missiles on him. Wait till you regen HP and repeat. Make sure you engage him when you're in front of him to get as much damage off as possible. Also, clean the eggs as they can spawn ultralisks. Since we killed both spawners and cleaning the eggs, there shouldn't be any ultraslisk and it should be a piece of cake.


Hellfire Missile Batteries are your best friends. The Brain Bug's slow move speed makes it very easy to slowly barrage down, Gatling Turrets can provide a little more damage as well, and Flaming Betties can help slow down the Ultralisks. Engaging the Bug in melee combat is possible, but be careful not to take too much damage or get trapped by the eggs.

Tankz tactic[]

Put up 6-7 hellfire batteries on the top of the ledge where he is, put 15-20 satellite turrets up. click on brainbug, he dies before he gets around the corner.

Extra trick - If you lack damage to kill the brain bug before he reaches the outer base, block narrow passage west from that ledge (where enemies are coming from) with Gatling Turret and Flaming Betty next to each other. That will make him go back and give you twice the time to kill him.

Also, Gatling Turret with range talent and satellite turrets should be able to reach him from that position as well.


On the one hand, Force Fields, Thunderstorm, and Nexus Exiles will help keep the Ultralisks at bay. On the other hand, the Brain Bug's Psionic type makes Thunderstorm more effective against it. Your shields are strong enough that you should be able to survive fighting the Bug directly for short spans of time, but be careful with the movement slow.

Tankz tactic[]

Nuke the spawners like in the tychus tactic, engage him and keep storming him on CD. With pierece + weapon research, you can outrange his AOE and just keep hitting him till he dies. Clean the eggs to avoid ultra spawns. If you get any, just FF behind you and keep dpsing him down.


Snipe has two Talents that give it bonus damage against Psionic and Heroic units. These make it an extremely powerful weapon against the Brain Bug. Apart from that, Nova's long attack range allows her to Strafe from the edge of the Gas. Avoid getting caught in Eggs or Ultralisks and Nova is probably the best hero to take this boss down.

Tankz tactic[]

Snipe him from the high ground to engage him, if you don't have enough range, just pull him, run back and spam snipes into him till he dies. Nuke the ultra dens first.

Serban tactic[]

Let the Bug pass you, then start shooting from behind strafing whenever you can. The Bug will change its path every now and then so make sure you reposition to strafe from behind. Given Nova's range and the Bug's movement rate, you'll stay outside the moving cloud and barely take any damage even when you get the upgrade to cancel the movement penalty for strafe. Be careful that mobs may still come from behind and you could end up sandwiched between the Bug and the mobs, so make sure Displace is available to be cast, just in case. When the Bug becomes active, you should have researched Lightweight Equipment Mastery and Killer Instinct Mastery. The former reduces the cooldown for strafe and the latter pretty much gives you infinite energy so keep strafing to replenish energy and take out whatever pops out of the Bug's eggs if you're surrounded.


You have no damage so you won't kill the Bug quickly, but your health and regeneration are high enough that you are effectively immune to Gas apart from the slow. Iron Man Mastery makes you nearly immune to the slow as well, but this boss alone would not justify taking it. You can either chase the Bug around the map and bleed it out with Irradiate or you can take on the swarms of Ultralisks trying to break down the base.

Tankz tactic[]

Stay inside of him all the time, don't bother attacking him if you can't attack + run at the same time and just spam your beam on CD. he can't kill you and will eventually go down.

Ignore the eggs. You should be able to kill the Bug quick enough with upgraded Corona and Irradiate. Typically 5-10 ultras total will spawn from eggs and should be no problem dealing with.

Major Anvil[]

Similar to Swann, the Bug's low move speed makes it very easy for you to set up a siege position and rain shells on it. Interestingly enough though, one of the few patterns in the Bug's movement causes it to attempt to avoid a Siege Mode Anvil. Tank Mode is also useful to kite Ultralisks and attack the Bug while chasing it around.

Tankz tactic[]

Kill the ultra spawners, engage him from the high ground in siege mode and shoot him till he's gone. unsiege and either follow him while shooting him in tank mode if you have all the range talents (8.7 range with buff) or just keep sieging up when he's about to take corners. Again, since there's no ultras, this should be a piece of cake.