Wheel of Misfortune + Mindslaver + Hypersonic Dragon

Wheel of Misfortune

Mindslaver

Hypersonic Dragon

How it works

1. Activate Mindslaver by paying 4, tapping it, and sacrificing it, gaining control of them during their next turn.
2. Move to their turn.
3. Cast Wheel of Misfortune for 2, selecting an arbitrarily large number for the opponent you control, and dealing that much damage to the opponent if the oponent chose the largest number.
4. If the opponent didn't choose the largest number, Wheel of Misfortune deals that much damage to each opponent who chose the largest number.