Flumph, Master of All

When Flumph enters the battlefield, all opponents
take X damage, and you gain health equal to X
times the number of opponents.
{x}{b} Target creature permanently gets -X/-X
{x}{w} Target creature permanently gets +X/+X
{10}{w}{w}{u}{u}{b}{b}{r}{r}{g}{g} You win the game
Rule #1: Always trust a flumph - X the mystic