Sacrifice

As an additional cost to cast this spell, sacrifice a creature.
Add an amount of {B} equal to the sacrificed creature's mana value.

Cabal Ritual

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

Culling the Weak

As an additional cost to cast this spell, sacrifice a creature.
Add {B}{B}{B}{B}.

Dark Ritual

Songs of the Damned

Add {B} for each creature card in your graveyard.

Carnival of Souls

Whenever a creature enters, you lose 1 life and add {B}.

Rain of Filth

Until end of turn, lands you control gain "Sacrifice this land: Add {B}."

Vesper Ghoul

{T}, Pay 1 life: Add one mana of any color.

Varragoth, Bloodsky Sire

Deathtouch
Boast — {1}{B}: Target player searches their library for a card, then shuffles and puts that card on top. (Activate only if this creature attacked this turn and only once each turn.)