I'm going to start with the fact that Mind control/Cyborg Kenny aren't working the way they should as it often happens that the control effect doesn't disappear, which isn't very funny when it happens on Manbearpig... I also saw a Mind control not working at all, the character was still attacking me even though he was controled and having the icon to show for it.

And how can Lightning bolt one shot characters like Awesom-o or Manbearpig when it's meant to only deal about 250 damages? Another massive bug really costly when it happens against you

I also had issues with leveling up my toons, having to pay twice to get one level and even losing levels with my Gunslinger Kyle