Oketra the True [Amonkhet Prerelease Promos] Nightmare Horse Add an amount of {B}

Add an amount of {B} equal to the sacrificed creature's mana value

If it's a creature card

Set: Beta Edition Type: Instant Rarity: Uncommon Cost: {B} As an additional cost to cast this spell

Set: New Phyrexia Type: Sorcery Rarity: Rare Cost: {1}{B}{B} Search target opponent's library for a card and exile it face down

Oketra the True [Amonkhet Prerelease Promos] Nightmare Horse Add an amount of {B}Set: Amonkhet Prerelease Promos Type: Legendary Creature God Rarity: Mythic Cost: {3}{W} Double strike, indestructible Oketra the True can't attack or block unless you control at least three other creatures. {3}{W}: Create a 1 1 white Warrior creature token with vigilance.