Valkrem, Fervent Loreseeker

Flying, haste
Whenever Valkrem enters the battlefield or
attacks, exile the top card of your library. You
may play it until the end of your next turn.
{x}{r/w}: You may return a card in exile with mana
value X to its owner's graveyard. If you do,
Valkrem deals X damage to up to one target,
where X is that card's mana value.