Treacherous Vampire 
Creature — Vampire
Flying Whenever this creature attacks or blocks, sacrifice it unless you exile a card from your graveyard. Threshold — As long as seven or more cards are in your graveyard, this creature gets +2/+2 and has "When this creature dies, you lose 6 life."
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL