This happened to me last night. Solid DPS group. Said just burn the boss i'll deal with adds (whm). They didn't die by the end of the round we had a HUGE group off ton's at zero hp.

As for people saying they don't do any dmg i'd say wrong. I'm a mostly i90 Whm and about 10% of boss HP left they just randomly turned on me and oneshotted me. They don't do much dmg but when you've got like 20 of them it F's you up!!!!!