Jet Medallion

Black spells you cast cost {1} less to cast.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Underworld Dreams

Whenever an opponent draws a card, this enchantment deals 1 damage to that player.

Dark Ritual

Seizan, Perverter of Truth

At the beginning of each player's upkeep, that player loses 2 life and draws two cards.

Crypt Ghast

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever you tap a Swamp for mana, add an additional {B}.

Gray Merchant of Asphodel

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)