Anti-ability. It's a passive skill, wuch can not be turned off which turns every ability cast on the person into the opposite.
Many times it comes in handy, for instance if someone where to curse you with a curse of slowness you'd just be faster. If someone would try to take over your mind you'd automatically take over theirs.
But it can also be troublesome if your new teammate wants to heal you, but you suffer damage instead.

















