I got a quest to use Fire Storm five times and I noticed something strange. I used the ability when my crusaders were running in because I was just trying to get the counter up, but it didn't actually cast. When I actually cast it and checked the counter I saw that it had incremented by two. After 15 minutes I tried to use the ability as soon as my crusaders started running to the right side of the screen and I got the quest completion without the ability even going on cooldown.