Luminous Comet, Rookie Mage

{u/r}, {t}: Luminous Comet, Rookie Mage deals one damage to any target.
Whenever you cast an instant or sorcery or activate an ability of Luminous Comet, Rookie Mage, flip three coins. If all come up tails, reveal cards from the top of your library until you reveal an instant or sorcery. If a spell triggered this ability, counter it. Cast the revealed spell without paying its mana cost.