The Mightstone and Weakstone [The Brothers' War Prerelease Promos] Wraith Noble (Each {G} in the mana

(Each {G} in the mana costs of permanents you control counts toward your devotion to green

and has "Whenever a player casts a spell or a creature attacks

where X is the number of cards revealed this way

Set: Mystery Booster 2 Type: Instant Rarity: Common Cost: {B} As an additional cost to cast this spell

Looks more like a shawl of branches to me

The Mightstone and Weakstone [The Brothers' War Prerelease Promos] Wraith Noble (Each {G} in the manaSet: The Brothers' War Prerelease Promos Type: Legendary Artifact Powerstone Rarity: Rare Cost: {5} When The Mightstone and Weakstone enters the battlefield, choose one Draw two cards. Target creature gets 5 5 until end of turn. {T}: Add {C}{C}. This mana can't be spent to cast nonartifact spells. (Melds with Urza, Lord Protector.)