Witch's Oven

{T}, Sacrifice a creature: Create a Food token. If the sacrificed creature's toughness was 4 or greater, create two Food tokens instead. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Gravelighter

Flying
When Gravelighter enters, draw a card if a creature died this turn. Otherwise, each player sacrifices a creature.

Accursed Marauder

When Accursed Marauder enters, each player sacrifices a nontoken creature.

Swamp

Consuming Sepulcher

At the beginning of your upkeep, each opponent loses 1 life and you gain 1 life.

Tithing Blade

When Tithing Blade enters, each opponent sacrifices a creature.
Craft with creature {4}{B} ({4}{B}, Exile this artifact, Exile a creature you control or a creature card from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Tithing Blade // Consuming Sepulcher

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Ayara, First of Locthwain

Whenever Ayara, First of Locthwain or another black creature you control enters, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: Draw a card.

Cauldron Familiar

When Cauldron Familiar enters, each opponent loses 1 life and you gain 1 life.
Sacrifice a Food: Return Cauldron Familiar from your graveyard to the battlefield.

Merciless Executioner

When Merciless Executioner enters, each player sacrifices a creature.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.