I encounter a bug wherein I used Elspeth's -3 ability to destroy a creature mana value three or less. My opponent had a Tezzeret that he had ultimatited and then used hte ability to turn a starcage pinnacle into a creature. My Elspeth destroyed it, but the game momentarily froze up, then the creatures that were exiled with the starcage reentered the battlefield under my control, as did the starcage, still as a creature. This happened twice in one game.