Vex, Friend Of The Winner

At the beginning of your upkeep, you may put a
Friend or Foe counter on target player.
Friend - Whenever a player with a friend
counter plays a spell, you may copy that spell.
Foe - Whenever a player with a Foe counter casts a spell that would
target a spell you control,
counter that spell unless they pay {x} where X is
Vex, Friend Of The Winner's power.