Masta Mixa
From RoR Wiki
Masta Mixa is the lvl 40 Night Goblin hero boss of the Gunbad Lab, the right wing in Gunbad.
His encounter is a public quest and from the gold bag you can loot the helm piece of the Redeye Set.
Tactic
Tank Masta Mixa against a pillar or the cauldrons, since he regularly punts the maintank.
Occasionally he summons his trusty staff Gitzappa da Stick. It stuns one groupmember as long as it is alive, so focus it down quickly after it spawns.
Furthermore green hands will spawn from time to time following one groupmember. They pound the ground and deal AOE damage, so whoever is chased by hands should move away from the group.
Any adds that come up during the fight can be cleaved, as they have very low health.