Red Bull

Enchant creature
Energy 2 (Red Bull enters the battlefield with three
energy counters on it. At the beginning of your upkeep, remove an energy counter from it.)
As long as there are energy counters on Red Bull, enchanted creature gets +2/+2 and has flying.
As long as there are no energy counters on Red
Bull, enchanted creature can't attack.
Legends tell of a potion that can give you wings.