Hero card

Billowing Shriekmass

Creature – Spirit

Value on arrivalDoes its thing as it enters: worth it from the first moment

Needs: Graveyard

Gives: Mill, Graveyard, Flyers

Not in winning lists yet: read from the card text and the graph

Build a deck with Billowing Shriekmass as the hero

Makes it work

Theorix Metamage · Void Extrapolator · Mind Drill Assailant · The Everflowing Well · Most Decrepit Old Bird · Platypus-Bear · Starving Revenant · Yathan Roadwatcher

Benefits from it

Call a Surprise Witness · The Ancient One · Chupacabra Echo

Use instead if you don't have it

Theorix Metamage · Bloodletter of Aclazotz · Moonstone, Harsh Mistress · Crow of Dark Tidings · Dawnhand Eulogist · Neriv, Heart of the Storm

Cards in the meta that answer it

Countersculpt (Azorius Control) · Get Lost (Azorius Control) · Jeskai Revelation (4-Color Control) · Inevitable Defeat (4-Color Control)