When AI has a full field of permanents and a full hand that includes Steal, the AI is destroying one of my permanents every turn for free.
My reasoning (besides the 'wtf why the hell are my permanents disappearing?') is that with my Mindgate I knew the AI had Steal coming up, and it started happening the next turn. Once all my nonpillar permanents were destroyed, it stole a quantum tower, which it could put into play even with a full field because it had a stack of quantum towers already, and then the steal was displayed normally and used up, and then my permanents stopped disappearing. I played some more permanents afterwards to test it and they were not destroyed.
edit: Later in the game it happened again, and it has nothing to do with the AI having a full hand, because it didn't the second time around. I think it just is getting confused when it has nowhere to put the stolen permanent.