The Great Henge

Mana Cost: {7}{G}{G}
Total Cost: 9
Type: Legendary Artifact
Description: This spell costs {X} less to cast, where X is the greatest power among creatures you control.
{T}: Add {G}{G}. You gain 2 life.
Whenever a nontoken creature you control enters, put a +1/+1 counter on it and draw a card.
Colors: G