Tira-Owl of Redkeep

Flying, vigilance
Whenever Tira-Owl of Redkeep deals combat
damage to a player, reveal one card from the top
of your library for each opponent, they take
damage equal to that card's converted mana cost.
Put cards revealed this way into the graveyard.
{2}, {t}: Add {u}{b}{r}{g}. Spend this mana only to
cast instant and/or sorcery spells.