Snow-Covered Swamp

Overeager Apprentice

Discard a card, Sacrifice this creature: Add {B}{B}{B}.

Ashnod's Altar

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Dark Ritual

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Grief

Menace
When this creature enters, target opponent reveals their hand. You choose a nonland card from it. That player discards that card.
Evoke—Exile a black card from your hand.

Tombstone Stairwell

Cumulative upkeep {1}{B} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
At the beginning of each upkeep, if this enchantment is on the battlefield, each player creates a 2/2 black Zombie creature token with haste named Tombspawn for each creature card in their graveyard.
At the beginning of each end step and when this enchantment leaves the battlefield, destroy all tokens created with this enchantment. They can't be regenerated.

Cabal Ritual

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

Carnival of Souls

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

Shepherd of Rot

{T}: Each player loses 1 life for each Zombie on the battlefield.

Blood Pet

Street Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Cycling—Pay 2 life. (Pay 2 life, Discard this card: Draw a card.)