Prisarium, the Rainbow Dragon

When Prisarium, the Rainbow Dragon enters the battlefield, add 100 mana of any color to your mana pool.
{x}{x}{w}{w}{u}{u}{b}{b}{r}{r}{g}{g}, {t}: Prisarium, the Rainbow dragon deals X damage to target player.
{ut}: Exile Prisarium, the Rainbow Dragon from the battlefield, then return him onto the battlefield under your control.