Creature — Vampire Horror
3 / 3
Flying
Sacrifice three other creatures: Transform this creature.
Madness



(If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)
Creature — Eldrazi Vampire
6 / 5
Flying
When this creature transforms into Abolisher of Bloodlines, target opponent sacrifices three creatures of their choice.
Madness works independently of why you're discarding the card. You could discard it to pay a cost, because a spell or ability tells you to, or because you have too many cards in your hand during your cleanup step. You can't discard a card with madness just because you want to, though.