The Mightstone and Weakstone [The Brothers' War Prerelease Promos] 078 attach it to target legendary

attach it to target legendary creature you control

that source deals double that damage to that player or permanent instead

Set: XY: Fates Collide Type: Supporter Rarity: Ultra Rare

Treasures you control have "{T}

Set: Sun & Moon: Hidden Fates - Shiny Vault Type: Lightning Rarity: Ultra Rare Retreat cost: Colorless

The Mightstone and Weakstone [The Brothers' War Prerelease Promos] 078 attach it to target legendarySet: 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.)