UDK IN THE ARENA
In arena matches I have seen this several times now, since the 6.2 patch. When fighting against UDK. Tyrant and my UDK go to attack the other UDK and the attack just does not happen at all. It just goes directly to the next champions turn. Also I was fighting a battle earlier today and UDK stood there for 10 minutes with 0 health showing with 4 of my 60 level champs hitting him. I mean 0 health showing all the way through this. Might be some things to look at. Maybe not.