Xerex Squire (Unknown Event UU03c) - Uncommon Magic: The Gathering Card

Whenever Xerex Squire attacks, calculate the hypotenuse of another creature you control. Xerex Squire's power and toughness become equal to that number, rounded up, until end of turn. (To calculate a hypotenuse, let A be that creature's power and B be that creature's toughness. Then C = √(a² + b²). C is the hypotenuse. Or just look up a calculator online.)