Walking over to the workbench area spawns this guy.
2 adds - they are mezzable and immune to pierce;
Dinree also power drains, so feed the MT.
The stun/silence that this guy has are nasty, so most DPS should attack from range out of AE if possible. Although this is reduced overall DPS, this should help the MT maintain agro.
Healers should try to cure the stun/stifle as much as possible, while casters feed the MT mana.
You must kill the named first, or badass adds will spawn.