Flying

Whenever you cast a spell with converted mana cost X, you may pay X life. If you do, put a number of +1/+1 counters on Venger equal to the converted mana cost of that spell.

{B}{R}, Sacrifice a creature: Choose one: Venger deals X damage to target creature or planeswalker, where X is the sacrificed creature's power; or draw X cards, where X is the sacrificed creature's toughness.