This is happening right now, in Arena, against prezoelf's deck (Gold league). The AI is destroying a lot of permanents (i.e. not a once-in-a-lifetime happening) without playing cards or activating abilities.
Quick facts:
Enemy permanent slots are full when this happens (I think I've read something about multiple Perm destruction when this happened)
PC in enemy's deck: Explosions, Pulverizers, Steals, Crusaders
Enemy has 2x draw, 2x deck
I'm 100% sure this wasn't the result of PC spells, as I was obviously paying close attention to the match when this began to happen
Every permanent is destroyed after a card is played. Then, legit (aka not bug) PC applies
(The turns before this, more shards decided to disappear, along with some sancs/towers/hgs, but I wasn't too sure about what was happenning)