Not to mention, Repopulate totally hoses Living Death.
I've had some trouble narrowing down my choices, however, two deck builders and a creature came to my mind, Pyromancy, Second Chance, and Mother of Runes. Even though my group has always had a fondness for Second Chance, oftentimes with hilarious results, trying for an infinite turn combo isn't quite as casual as trying to fling a Polar Kraken at someone, so it comes down to Pyromancy v. Mother of Runes. Mother of Runes is quite good, but I feel it is still casual because it is essentially a card that protects creatures and encourages actual combat phases and other neat tricks. Still, probably not as casual as pitching a Degree of Annihilation at someone. I nominate Pyromancy.
I've had some trouble narrowing down my choices, however, two deck builders and a creature came to my mind, Pyromancy, Second Chance, and Mother of Runes. Even though my group has always had a fondness for Second Chance, oftentimes with hilarious results, trying for an infinite turn combo isn't quite as casual as trying to fling a Polar Kraken at someone, so it comes down to Pyromancy v. Mother of Runes. Mother of Runes is quite good, but I feel it is still casual because it is essentially a card that protects creatures and encourages actual combat phases and other neat tricks. Still, probably not as casual as pitching a Degree of Annihilation at someone. I nominate Pyromancy.