Dread Return

Return target creature card from your graveyard to the battlefield.
Flashback—Sacrifice three creatures. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Agadeem, the Undercrypt

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}.

Agadeem's Awakening

Return from your graveyard to the battlefield any number of target creature cards that each have a different mana value X or less.

Agadeem's Awakening // Agadeem, the Undercrypt

Unmask

You may exile a black card from your hand rather than pay this spell's mana cost.
Target player reveals their hand. You choose a nonland card from it. That player discards that card.

Simian Spirit Guide

Bridge from Below

Whenever a nontoken creature is put into your graveyard from the battlefield, if this card is in your graveyard, create a 2/2 black Zombie creature token.
When a creature is put into an opponent's graveyard from the battlefield, if this card is in your graveyard, exile this card.

Memory's Journey

Target player shuffles up to three target cards from their graveyard into their library.
Flashback {G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Elvish Spirit Guide

Exile this creature from your hand: Add {G}.

Thassa's Oracle

When this creature enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Cabal Therapy

Choose a nonland card name. Target player reveals their hand and discards all cards with that name.
Flashback—Sacrifice a creature. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Jack-o'-Lantern

{1}, {T}, Sacrifice this artifact: Exile up to one target card from a graveyard. Draw a card.
{1}, Exile this card from your graveyard: Add one mana of any color.

Lotus Petal

{T}, Sacrifice this artifact: Add one mana of any color.

Undercity Informer

{1}, Sacrifice a creature: Target player reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Balustrade Spy

Flying
When this creature enters, target player reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Thoughtseize

Target player reveals their hand. You choose a nonland card from it. That player discards that card. You lose 2 life.

Cabal Ritual

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

Poxwalkers

Deathtouch
Curse of the Walking Pox — Whenever you cast a spell from anywhere other than your hand, return this card from your graveyard to the battlefield tapped.

Narcomoeba

Flying
When this card is put into your graveyard from your library, you may put it onto the battlefield.

Fell Mire

Fell the Profane

Fell the Profane // Fell Mire

Dark Ritual

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.