Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Have

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Necropolis Fiend

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Flying
{X}, {T}, Exile X cards from your graveyard: Target creature gets -X/-X until end of turn.

Raise Dead

Return target creature card from your graveyard to your hand.

Crippling Blight

Enchant creature
Enchanted creature gets -1/-1 and can't block.

Swamp

Hunted Nightmare

Menace
When Hunted Nightmare enters, target opponent puts a deathtouch counter on a creature they control.

Memory Leak

Target opponent reveals their hand. You choose a nonland card from that player's graveyard or hand and exile it.
Cycling {1} ({1}, Discard this card: Draw a card.)

Dark Ritual

Ash Barrens

{T}: Add {C}.
Basic landcycling {1} ({1}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Pharika's Spawn

Escape—{5}{B}, Exile three other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Pharika's Spawn escapes with two +1/+1 counters on it. When it enters this way, each opponent sacrifices a non-Gorgon creature of their choice.

Heartless Act

Choose one —
• Destroy target creature with no counters on it.
• Remove up to three counters from target creature.

Gravedigger

When Gravedigger enters, you may return target creature card from your graveyard to your hand.

Easy Prey

Destroy target creature with mana value 2 or less.
Cycling {2} ({2}, Discard this card: Draw a card.)

Sewer Nemesis

As Sewer Nemesis enters, choose a player.
Sewer Nemesis's power and toughness are each equal to the number of cards in the chosen player's graveyard.
Whenever the chosen player casts a spell, that player mills a card.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Untamed Hunger

Enchant creature
Enchanted creature gets +2/+1 and has menace. (It can't be blocked except by two or more creatures.)

Unbreakable Bond

Return target creature card from your graveyard to the battlefield with a lifelink counter on it.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Dead Weight

Enchant creature
Enchanted creature gets -2/-2.

Unshakable Tail

When Unshakable Tail enters and at the beginning of your upkeep, surveil 1.
Whenever one or more creature cards are put into your graveyard from your library, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{2}, Sacrifice a Clue: Return Unshakable Tail from your graveyard to your hand.

Blight-Breath Catoblepas

When Blight-Breath Catoblepas enters, target creature an opponent controls gets -X/-X until end of turn, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Corpse Churn

Mill three cards, then you may return a creature card from your graveyard to your hand. (To mill three cards, put the top three cards of your library into your graveyard.)

Underworld Charger

Underworld Charger can't block.
Escape—{4}{B}, Exile three other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Underworld Charger escapes with two +1/+1 counters on it.

Honored Heirloom

{T}: Add one mana of any color.
{2}, {T}: Exile target card from a graveyard.

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Bringer of the Last Gift

Flying
When Bringer of the Last Gift enters, if you cast it, each player sacrifices all other creatures they control. Then each player returns all creature cards from their graveyard that weren't put there this way to the battlefield.

Nighthowler

Bestow {2}{B}{B} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Nighthowler and enchanted creature each get +X/+X, where X is the number of creature cards in all graveyards.

Ransack the Lab

Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Bag of Holding

Whenever you discard a card, exile that card from your graveyard.
{2}, {T}: Draw a card, then discard a card.
{4}, {T}, Sacrifice Bag of Holding: Return all cards exiled with Bag of Holding to their owner's hand.

Venomous Hierophant

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When Venomous Hierophant enters, mill three cards. (Put the top three cards of your library into your graveyard.)

Extinction Event

Choose odd or even. Exile each creature with mana value of the chosen quality. (Zero is even.)

Snarling Gorehound

Menace
Whenever another creature you control with power 2 or less enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Sol Ring

Dark Bargain

Look at the top three cards of your library. Put two of them into your hand and the other into your graveyard. Dark Bargain deals 2 damage to you.

Bonder's Ornament

{T}: Add one mana of any color.
{4}, {T}: Each player who controls a permanent named Bonder's Ornament draws a card.