As i was doing the wind rider quest at thousand needles i come across a skull gnome mage who attacked me.
But the suspicious thing was that he was attacking every horde exept on warlock that was near him. So as a rogue i followed him and saw that he was gathering mobs standed still for a little time and the the warlock was following and did some aoe to tag the mobs. Then the warlock was standing still and the mage came in again and finish the mobs.
. I have more screenshots of them doing the same thing if needed