This article is about the original 40-man version of Grobbulus introduced in Patch 1.11. For the 10 and 25-man versions of the raid boss introduced in Wrath of the Lich King, see Grobbulus.


  • Enrages at 12 minutes mark.
  • Poison Cloud Emits a poison cloud 10 yards wide. The cloud deals high amounts of Nature damage, meaning the MT needs to keep moving while tanking. The poison cloud remains for a very long time.
  • Slime Spray Hits for 3600-4800 Nature damage. Party members who are hit will spawn a Fallout Slime.
  • Fallout slime A Blob that deals 300dmg/2seconds, in a 10 yard range AoE.
  • Mutating Injection Injects a target with a mutagen that will do a 4500 physical damage AoE after 10 sec, or a lower-damage AoE when cleansed. The target will create a poison cloud with the same effect as Grobbulus himself, so the target will need to run to the side when cleansed to avoid damaging the rest of the raid.
  • Slime Stream is an AoE DoT deals 4500 Nature damage over 3 sec. This ability is considered to be triggered when the MT gets out of the melee range of Grobbulus(this may occur when MT is passing a corner and adjusting his position). Another theory about Slime Stream is the ranged highest threat-holder gets too close to Grobbulus.


The maintank stands upon the ramp which Grobbulus patrols, slowly moving him to avoid his poison cloud attack. The MT hugs the outside wall all the way around the room. Grobbulus should be moved as slowly as possible for the best use of space, as his cloud will limit the room's safe zone.

DPS on Grobbulus is ranged, so as to avoid spawning multiple fallout slimes. Only one slime should be spawned at a time(the MT's) which will presumably aggro onto a healer, and should otherwise be pulled to melee classes. They dispatch this slime, away from the ranged/healers, then return to adding ranged dps.

Injected people should run to the edge of existing clouds, as far away from the the raid as possible to best use the space. At 30% Grobbulus injects people more frequently and safe space can become scarce if it is not used well from the beginning.

  • Note: If you cleanse that person that is Injected, make sure they are at the location you want them to be. Cleanse will lower the amount of damage you take, but it will start the AoE where they are standing.

Sometimes the ramp seems safe but there is a poison cloud effect at the base of the ramp. This happens when a cloud grows under the ramp and hits people that go over the ramp (even when ramp seems to be clear)

Everyone always needs to be aware of the growing green clouds at all times.


Grobbulus at lvl 70

  • It is possible for the maintank to stay at one location for the duration of the fight. In order to make the fight easier however, it is effective to use two spots, moving from one to the other and then back when the first spot is clear of clouds.


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