Ancient Scaleweaver

When Ancient Scaleweaver enters or leaves the battlefield, create a 3/3 white and green Wurm creature token.
{t}, Sacrifice a Wurm card: Choose one;
-When you cast Wurm cards this turn, reduce their colorless mana cost by up to a total of X.
-Remove up to a total of Y Commander Damage.
-Gain Z life.
X is the sacrificed Wurm card's Power, Y is it's Toughness and Z is it's converted mana cost.
Activate only during your main phase.