Energy Vortex

As Energy Vortex enters the battlefield, choose an opponent.

At the beginning of your upkeep, remove all energy counters from Energy Vortex.

At the beginning of the chosen player's upkeep, Energy Vortex deals 3 damage to that player unless he/she pays [1] for each energy counter on Energy Vortex.

[Variable Colorless]: Put X energy counters on Energy Vortex. Activate this ability only during your upkeep.