Chromaggus is the seventh boss in Blackwing Lair, the last guardian before facing Nefarian.

Chromaggus is easy to kill at 85, but it's worth noting that he radiates Brood Afflictions which debuff everyone in the zone. These are:

• Brood Affliction: Red: Disease. 50 Fire damage every three seconds. Heals Chromaggus on death.
• Brood Affliction: Green: Poison. Healing reduced by 50%, 250 Nature damage every 5 seconds.
• Brood Affliction: Blue: Magic. Movement slowed by 70%. Casting speed reduced by 50%. 50 mana and 1 health drained per second.
• Brood Affliction: Black: Curse. Fire Damage increased by 100%.
• Brood Affliction: Bronze: 4 second stun at random intervals for 10 minutes. Can only be removed with Hourglass Sand.

When a player gets all five afflictions, they will undergo a Chromatic Mutation, turning into a Chromatic Drakonid under the control of Chromaggus. This mutation cannot be dispelled and will persist for five minutes. Like most forms of mind control or mutation in legacy dungeons, the player does surprisingly significant damage while turned into this at level 85 and can easily two or three shot a fellow player so avoid this at all costs.

You can also tame Chromaggus for an unique skin.

This NPC can be found in Blackwing Lair.