Constant Mists [Stronghold] Kor Artificer Nightmare's power and toughness are

Nightmare's power and toughness are each equal to the number of Swamps you control

Set: EX: Crystal Guardians Type: Fire Rarity: Common Retreat cost: Colorless

Set: POP Series 6 Type: Lightning Rarity: Rare Retreat cost: Colorless

Imaginary Friend

Set: Alpha Edition Type: Creature — Human Assassin Rarity: Rare Cost: {1}{B}{B} {T}: Destroy target tapped creature

Constant Mists [Stronghold] Kor Artificer Nightmare's power and toughness areSet: Stronghold Type: Instant Rarity: Uncommon Cost: {1}{G} BuybackSacrifice a land. (You may sacrifice a land in addition to any other costs as you cast this spell. If you do, put this card into your hand as it resolves.) Prevent all combat damage that would be dealt this turn.