While playing Standard Brawl on PC client, across several games, using Professor Dellian Fel's -2 ability to destroy creatures would result in them sitting on the board in a state of summoning sickness. They would not be visible in the graveyard, you could not target them, and I do not not if my opponent was able to see the problem. Other removal spells and abilities would not have this problem. Certain cards would lose icons on them, such as "Commander" logos. In instances in which a Commander was replayed, there would be two instances of the card on the board, although only one would be targetable or display correctly and the other would have summoning sickness and be untargetable by effects.