Richard Garfield, Ph.D. essentially makes you play a variant of the Magic game called “Mental Magic.” Here’s how the game works. Whenever you cast a spell, you reveal the card to all players and choose any other card (see below for the cards that you can use) that has that card’s mana cost. (Note that color very much does matter.) That spell can then be cast as though it was the chosen card. You aren’t allowed to choose the same card twice.