Avatar of Woe

If there are ten or more creature cards total in all graveyards, this spell costs {6} less to cast.
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
{T}: Destroy target creature. It can't be regenerated.

Chupacabra Echo

Fathomless descent — When Chupacabra Echo enters, target creature an opponent controls gets -X/-X until end of turn, where X is the number of permanent cards in your graveyard.

Drakestown Forgotten

Drakestown Forgotten enters with X +1/+1 counters on it, where X is the number of creature cards in all graveyards.
{2}{B}, Remove a +1/+1 counter from Drakestown Forgotten: Target creature gets -1/-1 until end of turn.

Throne of Death

At the beginning of your upkeep, mill a card.
{2}{B}, {T}, Exile a creature card from your graveyard: Draw a card.

Egon, God of Death

Deathtouch
At the beginning of your upkeep, exile two cards from your graveyard. If you can't, sacrifice Egon and draw a card.

Egon, God of Death // Throne of Death

Graveblade Marauder

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever Graveblade Marauder deals combat damage to a player, that player loses life equal to the number of creature cards in your graveyard.

Bonehoard

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +X/+X, where X is the number of creature cards in all graveyards.
Equip {2}

Corpse Augur

When Corpse Augur dies, you draw X cards and you lose X life, where X is the number of creature cards in target player's graveyard.

Rise of the Dark Realms

Put all creature cards from all graveyards onto the battlefield under your control.

Darkblast

Target creature gets -1/-1 until end of turn.
Dredge 3 (If you would draw a card, you may mill three cards instead. If you do, return this card from your graveyard to your hand.)

Golgari Thug

When Golgari Thug dies, put target creature card from your graveyard on top of your library.
Dredge 4 (If you would draw a card, you may mill four cards instead. If you do, return this card from your graveyard to your hand.)

Cemetery Tampering

Hideaway 5 (When this enchantment enters, look at the top five cards of your library, exile one face down, then put the rest on the bottom in a random order.)
At the beginning of your upkeep, you may mill three cards. Then if there are twenty or more cards in your graveyard, you may play the exiled card without paying its mana cost.

Crypt of Agadeem

Crypt of Agadeem enters tapped.
{T}: Add {B}.
{2}, {T}: Add {B} for each black creature card in your graveyard.

Stinkweed Imp

Flying
Whenever Stinkweed Imp deals combat damage to a creature, destroy that creature.
Dredge 5 (If you would draw a card, you may mill five cards instead. If you do, return this card from your graveyard to your hand.)

Boneyard Mycodrax

Boneyard Mycodrax's power and toughness are each equal to the number of other creature cards in your graveyard.
Scavenge {4}{B} ({4}{B}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Apocalypse Demon

Flying
Apocalypse Demon's power and toughness are each equal to the number of cards in your graveyard.
At the beginning of your upkeep, tap Apocalypse Demon unless you sacrifice another creature.

Grave Strength

Choose target creature. Mill three cards, then put a +1/+1 counter on that creature for each creature card in your graveyard. (To mill three cards, put the top three cards of your library into your graveyard.)

Dakmor Salvage

Dakmor Salvage enters tapped.
{T}: Add {B}.
Dredge 2 (If you would draw a card, you may mill two cards instead. If you do, return this card from your graveyard to your hand.)

Necroplasm

At the beginning of your upkeep, put a +1/+1 counter on Necroplasm.
At the beginning of your end step, destroy each creature with mana value equal to the number of +1/+1 counters on Necroplasm.
Dredge 2 (If you would draw a card, you may mill two cards instead. If you do, return this card from your graveyard to your hand.)

Nightmare Void

Target player reveals their hand. You choose a card from it. That player discards that card.
Dredge 2 (If you would draw a card, you may mill two cards instead. If you do, return this card from your graveyard to your hand.)

Embodiment of Agonies

Flying, deathtouch
Embodiment of Agonies enters with a +1/+1 counter on it for each different mana cost among nonland cards in your graveyard. (For example, {2}{B} and {1}{B}{B} are different mana costs.)