Vashj'ir Honor Guard

Vashj'ir Honor Guard can be found in Serpentshrine Cavern and Coilfang Reservoir. He has intimidating shout, and enrages. Immune to stuns and crowd control. Has a knock-up-and-slightly-backwards ability; while tanking beware of any mobs that have not been cleared behind you, especially on the first group if Hydross the Unstable mobs are still around.

Strategies
Warriors should use Berserker's Rage at 40% to avoid aggro loss due to its Intimidating Shout.

Note
They likely come from Vashj'ir.