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.)