I had a very frustrating match because my creatures kept getting -2/-2 for no apparent reason. It turns out that the opponent had a Tetzimoc, Primal Death in hand and the game had entered Enraged Mode.
But there was no message that popped up nor was there any mention in the Battlelog. After I lost I saw that it was Tetzi’s passive ability in-hand that was killing my creatures.
Also seems odd that Enrage doubles the -1/-1, which isn’t damage.