Demon of Catastrophes

As an additional cost to cast this spell, sacrifice a creature.
Flying, trample

Dreadmalkin

Menace (This creature can't be blocked except by two or more creatures.)
{2}{B}, Sacrifice another creature or planeswalker: Put two +1/+1 counters on Dreadmalkin.

Murder

Banehound

Audacious Thief

Whenever Audacious Thief attacks, you draw a card and you lose 1 life.

Swamp

Diregraf Ghoul

Grasping Scoundrel

Grasping Scoundrel gets +1/+0 as long as it's attacking.

Hired Blade

Flash (You may cast this spell any time you could cast an instant.)

Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Vicious Offering

Kicker—Sacrifice a creature. (You may sacrifice a creature in addition to any other costs as you cast this spell.)
Target creature gets -2/-2 until end of turn. If this spell was kicked, that creature gets -5/-5 until end of turn instead.

Bladebrand

Target creature gains deathtouch until end of turn.
Draw a card.

Knight of the Ebon Legion

{2}{B}: Knight of the Ebon Legion gets +3/+3 and gains deathtouch until end of turn.
At the beginning of your end step, if a player lost 4 or more life this turn, put a +1/+1 counter on Knight of the Ebon Legion. (Damage causes loss of life.)

Disfigure

Target creature gets -2/-2 until end of turn.

Vampire of the Dire Moon

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Fathom Fleet Cutthroat

When Fathom Fleet Cutthroat enters, destroy target creature an opponent controls that was dealt damage this turn.