Command the Dreadhorde

Choose any number of target creature and/or planeswalker cards in graveyards. Command the Dreadhorde deals damage to you equal to the total mana value of those cards. Put them onto the battlefield under your control.

Abattoir Ghoul

First strike
Whenever a creature dealt damage by this creature this turn dies, you gain life equal to that creature's toughness.

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.

Dark Ritual

Warlock Class

(Gain the next level as a sorcery to add its ability.)
At the beginning of your end step, if a creature died this turn, each opponent loses 1 life.
{1}{B}: Level 2
When this Class becomes level 2, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
{6}{B}: Level 3
At the beginning of your end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Abyssal Specter

Flying
Whenever this creature deals damage to a player, that player discards a card.

Asphyxiate

Go Blank

Target player discards two cards. Then exile that player's graveyard.

Raiders' Wake

Whenever an opponent discards a card, that player loses 2 life.
Raid — At the beginning of your end step, if you attacked this turn, target opponent discards a card.

Ob Nixilis, the Hate-Twisted

Whenever an opponent draws a card, Ob Nixilis deals 1 damage to that player.
−2: Destroy target creature. Its controller draws two cards.

Malakir Cullblade

Whenever a creature an opponent controls dies, put a +1/+1 counter on this creature.

Doom Blade

Liliana's Specter

Flying
When this creature enters, each opponent discards a card.

Tenured Inkcaster

When this creature enters, put a +1/+1 counter on target creature.
Whenever a creature you control with a +1/+1 counter on it attacks, each opponent loses 1 life and you gain 1 life.

Ring of Xathrid

{2}: Regenerate equipped creature. (The next time that creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's black.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Diabolic Tutor

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

Skinrender

When this creature enters, put three -1/-1 counters on target creature.

Abyssal Horror

Flying
When this creature enters, target player discards two cards.

Tormented Thoughts

As an additional cost to cast this spell, sacrifice a creature.
Target player discards a number of cards equal to the sacrificed creature's power.