The Abyssal Great Wyrm

Flying, Menace
{x}: Target player puts the top X cards from their library into their graveyard.
{2}{b}{r}, {t}: Abyssal Great Wyrm deals 5 damage to target creature or planeswalker. If a creature dealt damage this way dies this turn, exile it instead. If an opponent exiled a card in this way, they lose 1 life for each card in their graveyard with a converted mana cost of 3 or more.