Consuming Penumbra

Enchant creature
At the beginning of your upkeep, choose a creature. Create a copy of Consuming Penumbra and attach it to that creature. You lose 2 life.
When Consuming Penumbra enters the battlefield, tap enchanted creature. Then, if that creature has 3 or more Auras named Consuming Penumbra attached to it, its controller sacrifices it and you gain life equal to its toughness.