First I apologize for the low resolution and also the fact that it is in Danish, but Bera had a Mana Generation stack that I can’t identify where it came from.
This was in a Tournament Raid (current Buff Booster tournament) and she has the +20% to attack due to having a Buff, but she also has a Mana Generation which is coming from somewhere I can’t identify.
None of my heroes apply a Mana Generation buff, let alone a Stack. While D’Andre on the enemy team can apply a Mana Gen buff, I have no hero who could have stolen it. Even then, D’Andre does not apply a Stack.