Percival, Nobleman of Revenge

Equipment spells cost {1} less to cast.

Whenever Percival attacks, if equipped, you may pay
{x} life, where {x} is Percival's power. If you do, deal that much damage to a creature you don't control.
If a legendary creature would die this way, put a vengeance counter on Percival.

At the end of your turn, if Percival has 6 or more vengeance counters, you win the game.