Dawn of the Final Night

If you cast this spell for its madness cost, it is a legendary sorcery card with "Each opponent loses 2 life for each card in your graveyard. Exile this card."
This card has power and toughness each equal to the number of cards in your graveyard.
Madness {2}{b}{b}
{2}{g}, Exile this card from your graveyard: You may cast this card for its madness cost as though you have just discarded it. If you don't, put it into its owner's graveyard.