Here's a puzzle straight from Mark Rosewater's book, Magic: The Puzzling. This one dates back to the days of Fourth Edition, but trust us, the answer still works using current rules.
Each card image is clickable if you don't know what it does. Give it a shot, and tune in Monday for the answer.
Your opponent is Paul. The duel has been very close but neither one of you has been able to finish off the other. Them on your turn, you draw an Enchantment Alteration, and you realize that the game is yours. It is the beginning of your [first] main phase. Defeat Paul this turn without dying yourself.