My wife and I are both playing the game. She’s had skullcrusher for longer than I. Hers is upgraded to 5 star, mine is a 4. Hers has a very high defense with artifacts (1000+ vs my 600). 

Here is the odd behavior - when fighting in arena her counterattack buff places on other players lasts a legitimate 2 rounds. When I place the buff it rarely lasts even one round. We’ve compared and see a clear difference. The difference in play result is huge. For her Skullcrusher is invaluable in arena for me he’s useless. His description doesn’t note that his duration changes with higher levels. Why is mine not staying on a full round? Bug?