Cabal Coffers

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

Seething Song

Rowan, Scion of War

Menace
{T}: Spells you cast this turn that are black and/or red cost {X} less to cast, where X is the amount of life you lost this turn. Activate only as a sorcery.

Sol Ring

Dark Ritual

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Swamp

Rakdos Signet

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Vessel of Volatility

{1}{R}, Sacrifice Vessel of Volatility: Add {R}{R}{R}{R}.

Mountain

Ruby Medallion

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

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. Talisman of Indulgence deals 1 damage to you.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Magmatic Galleon

When Magmatic Galleon enters, it deals 5 damage to target creature an opponent controls.
Whenever one or more creatures your opponents control are dealt excess noncombat damage, create a Treasure token.
Crew 2

Mana Geyser

Add {R} for each tapped land your opponents control.

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Jet Medallion

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

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}.