Was helping a friend run a dungeon on his 78 destro lock with a level 90. Everytime he cast any spell at all (even using his wand just to autoattack) he would immediately aggro whatever he was hitting. The boss could be at 20% health and the first button he hits would cause him to have threat.
He had no pet out. What could be causing this issue? He also has Grimoire of Sacrifice as his talent but he didn't have it in effect when this has been happening.