Sacrifice Blood Pet: Add {B}.

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)

I -- You may sacrifice a creature. If you do, each opponent discards a card.

II -- Return target creature card from your graveyard to your hand.

III -- Target opponent may sacrifice a nonland, nontoken permanent. If they don't, they lose 2 life and you draw a card.

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

When Chittering Witch enters the battlefield, create a number of 1/1 black Rat creature tokens equal to the number of opponents you have.

{1}{B}, Sacrifice a creature: Target creature gets -2/-2 until end of turn.

Clay Revenant enters the battlefield tapped.

{2}{B}: Return Clay Revenant from your graveyard to your hand.

Add {B}{B}{B}.

Enchant creature

Enchanted creature gets -2/-0.

When Despondency is put into a graveyard from the battlefield, return Despondency to its owner's hand.

As an additional cost to cast this spell, sacrifice a creature, discard a card, or pay 4 life.

When Dusk Mangler enters the battlefield, each opponent sacrifices a creature, discards a card, and loses 4 life.

Flying

When Marsh Flitter enters the battlefield, create two 1/1 black Goblin Rogue creature tokens.

Sacrifice a Goblin: Marsh Flitter has base power and toughness 3/3 until end of turn.

When Meteor Golem enters the battlefield, destroy target nonland permanent an opponent controls.

When Mycosynth Wellspring enters the battlefield or is put into a graveyard from the battlefield, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Flying

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)

Whenever Nefarox, Overlord of Grixis attacks alone, defending player sacrifices a creature.

Flying

Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of that creature, except it's 1/1 and it's a Nightmare in addition to its other types.

When Oath of Liliana enters the battlefield, each opponent sacrifices a creature.

At the beginning of each end step, if a planeswalker entered the battlefield under your control this turn, create a 2/2 black Zombie creature token.

Flash

When Omen of the Dead enters the battlefield, return target creature card from your graveyard to your hand.

{2}{B}, Sacrifice Omen of the Dead: Scry 2.

When Phyrexian Delver enters the battlefield, return target creature card from your graveyard to the battlefield. You lose life equal to that card's mana value.

When Sling-Gang Lieutenant enters the battlefield, create two 1/1 red Goblin creature tokens.

Sacrifice a Goblin: Target player loses 1 life and you gain 1 life.

Devoid (This card has no color.)

Flying

At the beginning of your upkeep, sacrifice a creature.

Whenever you sacrifice a creature, draw a card.

Return target creature card with mana value 3 or less from your graveyard to the battlefield.

Cycling {2} ({2}, Discard this card: Draw a card.)

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.