Hammer of Nazahn [Commander 2017] Vampire Shade you may exile a black

you may exile a black card from your hand rather than pay this spell's mana cost

Set: Innistrad: Crimson Vow Prerelease Promos Type: Creature — Dragon Rarity: Mythic Cost: {2}{R}{R} Flying

It is found here

Set: Secret Lair Drop Series Type: Artifact — Equipment Rarity: Rare Cost: {2} Equipped creature has haste and shroud

Whenever Key to the City becomes untapped

Hammer of Nazahn [Commander 2017] Vampire Shade you may exile a blackSet: Commander 2017 Type: Legendary Artifact Equipment Rarity: Rare Cost: {4} Whenever Hammer of Nazahn or another Equipment enters the battlefield under your control, you may attach that Equipment to target creature you control. Equipped creature gets +2 +0 and has indestructible. Equip {4}