Jet Medallion

Black spells you cast cost {1} less to cast.

Cover of Darkness

As Cover of Darkness enters, choose a creature type.
Creatures of the chosen type have fear. (They can't be blocked except by artifact creatures and/or black creatures.)

Diabolic Revelation

Search your library for up to X cards, put those cards into your hand, then shuffle.

Dark Ritual

Dread Cacodemon

When Dread Cacodemon enters, if you cast it from your hand, destroy all creatures your opponents control, then tap all other creatures you control.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Ob Nixilis, the Fallen

Landfall — Whenever a land you control enters, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis, the Fallen.

Caged Sun

As Caged Sun enters, choose a color.
Creatures you control of the chosen color get +1/+1.
Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Nantuko Shade

{B}: Nantuko Shade gets +1/+1 until end of turn.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Carnifex Demon

Flying
Carnifex Demon enters with two -1/-1 counters on it.
{B}, Remove a -1/-1 counter from Carnifex Demon: Put a -1/-1 counter on each other creature.

Quicksilver Amulet

{4}, {T}: You may put a creature card from your hand onto the battlefield.

Rune-Scarred Demon

Flying
When this creature enters, search your library for a card, put it into your hand, then shuffle.

Griselbrand

Flying, lifelink
Pay 7 life: Draw seven cards.

Urza's Incubator

As Urza's Incubator enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Visara the Dreadful

Flying
{T}: Destroy target creature. It can't be regenerated.

Reaper from the Abyss

Flying
Morbid — At the beginning of each end step, if a creature died this turn, destroy target non-Demon creature.

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature of their choice.

Nefarox, Overlord of Grixis

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 of their choice.

Royal Assassin

Diregraf Ghoul

Mark of the Oni

Enchant creature
You control enchanted creature.
At the beginning of the end step, if you control no Demons, sacrifice Mark of the Oni.

Wall of Souls

Defender (This creature can't attack.)
Whenever Wall of Souls is dealt combat damage, it deals that much damage to target opponent or planeswalker.

Victimize

Choose two target creature cards in your graveyard. Sacrifice a creature. If you do, return the chosen cards to the battlefield tapped.

Thoughtseize

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

Swamp

Reiver Demon

Flying
When Reiver Demon enters, if you cast it from your hand, destroy all nonartifact, nonblack creatures. They can't be regenerated.

Withengar Unbound

Flying, intimidate, trample (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a player loses the game, put thirteen +1/+1 counters on Withengar Unbound.

Elbrus, the Binding Blade

Equipped creature gets +1/+0.
When equipped creature deals combat damage to a player, unattach Elbrus, the Binding Blade, then transform it.
Equip {1}