Grobbulus Strategy Guide – Naxxramas (10)

wotlk classic naxxramas grobbulus featured image

Grobbulus is the second boss in the Construct Quarter of Naxxramas. Another abomination, this time reanimated and fueled by living ooze.

Grobbulus, the first of what was to be an army of flesh giants. It carried the plague slime of Naxxramas within its body, injecting the living ooze into the bodies of its foe. The recipient of this foul injection would usually flee to his allies, bringing them down with him.” –Commander Eligor Dawnbringer

Grobbulus is a fight that will always keep you on your toes, giving the raid very little time to stand still and focus on DPS, instead requiring everyone to be constantly adjusting and moving. This fight also requires a somewhat unique experience of not dispelling immediately, going against the muscle memory of many healers. As long as no one in your raid goes into autopilot this fight shouldn’t prove very difficult.

This guide will offer a detailed, step-by-step tutorial on how to deal with Grobbulus’ swathe of poison clouds and toxic injections.

Role Summaries

  • If you aren’t the main-tank, make sure you are never in front of the boss to avoid spawning extra Fallout Slime
  • Stick with your group as much as possible to make positioning easier
  • Keep your eye on your debuffs and move away from others immediately if you get Mutating Injection
  • Watch your feet for Poison Clouds
  • Focus down and kill Fallout Slimes immediately, if any happen to spawn
  • Focus down and kill Fallout Slimes immediately, if any happen to spawn
  • Don’t dispel too fast out of muscle memory! You must wait for people to move out of their stack before dispelling them


  • Plan your pull ahead of time, you don’t want the boss to accidentally slime the raid or create an impassable wall of Poison Clouds.


  • Keep an eye on all the Poison Clouds, making sure no one ends up in them as you reposition.
  • Do not turn the boss to the raid under any circumstances, always keep going in the opposite direction of the raid.
  • If you need to turn the boss 90 degrees, communicate this clearly so that no one is in front.



Grobbulus only has one Phase, but there are constantly things to keep an eye on. Most important for this fight is positioning, requiring the raid to always be careful where everyone is positioned so that nothing unexpected happens. The raid will be split into 3 areas for the entire fight. The main-tank by themselves in front, melee stacked behind, and ranged stacked away. These stacks should be adjusting with the tank constantly and a lot of the fight happens while moving.


Every 15-seconds or so, Grobbulus will drop a Poison Cloud at his feet, lasting for 75-seconds and dealing high damage to players that touch it. This is dealt with by simply always moving Grobbulus around the area, preferably sticking to the edges of the map to give your group as much space as possible.

Grobbulus sprays a 45-yard cone in front of him with slime, dealing 6300 to 7700 Nature damage and summoning a Fallout Slime for every target hit. This is easily managed by only ever having the main-tank be in front of Grobbulus , guaranteeing that you never spawn more than one Fallout Slime at a time, which can then easily be grabbed by the off-tank and burned down quickly.

Fallout Slimes deal constant Nature damage in a 10-yard AoE around them, so typically the ranged DPS should be focusing these down, while the melee DPS remain on Grobbulus to avoid this AoE damage.

Every 20-seconds or so, Grobbulus will inject a player with a Disease. After 10-seconds, or when dispelled, the recipient will drop a Poison Cloud at their feet, and everyone within 20-yards of the recipient (and the recipient themselves) will also take 8075 to 8925 Nature damage. This is typically dealt with by having the diseased player dip out of the fight, away from the groups before getting dispelled, saving the group from both the explosion and the cloud.

Raid Composition & Preparation

This fight has very few class or spec requirements, only requiring at least one Priest, Paladin, or Shaman for Cure Disease, Cleanse or Cleanse Spirit to deal with Mutating Injection.

Even though not required, you always want to cover a lot of the WotLK raid buffs and debuffs, as well as making sure you have Bloodlust/Heroism to maximize damage.

You will want 1-3 Healers for this fight, but if done right this fight is not very heavy on healing, as well as most healing being single-target.

There are no strict requirements for DPS classes or specs here, you simply want a combination of good raid buffs and debuffs, as well as the best players you can muster.

You will want 2 tanks for this fight: 1 main-tank that will be tanking Grobbulus for the entire fight, and 1 off-tank that will be picking up the slimes that spawn. The off-tank is typically the tank that can deal the most DPS, as they will be free to DPS the boss most of the fight.

The Pull

grobbulus frontal

Grobbulus patrols around a lot, going up and down the ramp in the corner of the room. It is recommended to immediately pull him away from the ramp as the height differences can sometimes break line of sight, giving DPS a difficult time and potentially making early positioning very messy.

The tank should attempt to immediately bring Grobbulus to a wall, while also making sure that Grobbulus never ends up facing the raid. The DPS should be trying to get into either the melee or ranged stack and should move together even while the tank repositions on the pull.

grobbulus positioning 1

The Fight

This fight will be the same from start until finish, with no Phases. Grobbulus should be tanked adjacent to a wall. Every 15-seconds Grobbulus will drop a Poison Cloud, requiring the tank to move him around the edge of the room so that no one ends up in the Poison Cloud.

Every so often Grobbulus will cast Slime Spray in a frontal cone, spawning a Fallout Slime for each player hit, which the off-tank should immediately pick up and bring away from the melee DPS while the ranged DPS kills it. Slime Spray needs to always only hit the main-tank, otherwise, it won’t take long for the raid to be overwhelmed by slimes.

Every 20-seconds or so, Grobbulus will debuff a raid member with Mutating Injection, a disease that will deal heavy damage to everyone within 20-yards of the target after 10-seconds or if it is dispelled. This is cast more often the lower Grobbulus health is. When the buff is dispelled or naturally falls off, it will also drop a Poison Cloud under the target’s feet.

This is the main mechanic for the DPS, but it can hit anyone. When they are debuffed they should immediately duck out of their stack and get at least 20-yards away from everyone, preferably straight back in the direction they came from, avoiding any Poison Clouds already there.

To deal with this, it is best if non-tanks are stacked in two groups, one for ranged and one for melee. This makes it a lot easier for the person with Mutating Injection to simply move away from their group without having to worry about anyone in odd spots getting in the way.

When players with Mutating Injection are far enough from the raid, they should be dispelled as soon as possible, so that they can return to the fight with minimal downtime. If done correctly only the player with the debuff will take damage, and on one target it is easily healable.

If everything is done smoothly, no one should really be in any danger during the fight, but any one player not paying attention could immediately spiral the fight for everyone.

Here are some of the main things that can typically go wrong in this phase:

  • Someone is in front of the boss that shouldn’t be and consequently spawns extra slimes
  • Someone with Mutating Injection does not react and stays put in their stack, spawning a Poison Cloud on them and dealing damage to everyone, including the tank if in melee
  • A dispeller reacts out of muscle memory and instantly dispels Mutating Injection, spawning a Poison Cloud on a stack and damaging everyone
  • The off-tank doesn’t pick up the Fallout Slime in time and it creates chaos, potentially leading to people panicking and repositioning poorly
  • The main-tank moves poorly, cutting off large areas of the arena with Poison Clouds

If everyone is paying attention and are on the same page, this fight shouldn’t be a problem for most raid groups, especially if you have already beaten Patchwerk.

Congratulations on defeating Grobbulus, claim your loot and make sure if anyone still has Mutating Injection that they move away from the group, no one wants to die after the fight! Carry on to the hardest challenge in Naxxramas — Walking in a straight line over a pipe.


About the Author


I love MMOs of all shades, especially the nitty gritty numbers parts of them. You might recognize me from the Shadow Priest discord, otherwise I play a little bit of everything, especially games with support roles available.
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