Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Duskwalker

Kicker {3}{B} (You may pay an additional {3}{B} as you cast this spell.)
If this creature was kicked, it enters with two +1/+1 counters on it and with fear. (It can't be blocked except by artifact creatures and/or black creatures.)

Cloudpiercer

Mutate {3}{R} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Reach
Whenever this creature mutates, you may discard a card. If you do, draw a card.

Swarming Goblins

When this creature enters, roll a d20.
1—9 | Create a 1/1 red Goblin creature token.
10—19 | Create two of those tokens.
20 | Create three of those tokens.

Krenko's Command

Create two 1/1 red Goblin creature tokens.

Bituminous Blast

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Bituminous Blast deals 4 damage to target creature.

Diabolic Edict

Target player sacrifices a creature of their choice.

Mountain

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Mugging

Mugging deals 2 damage to target creature. That creature can't block this turn.

Black Dragon

Flying
Acid Breath — When this creature enters, target creature an opponent controls gets -3/-3 until end of turn.

Dark Ritual

Gravedigger

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

Swamp

Reassembling Skeleton

{1}{B}: Return this card from your graveyard to the battlefield tapped.

Dread Shade

{B}: This creature gets +1/+1 until end of turn.

Malicious Invader

Flying
This creature gets +2/+0 as long as an opponent controls a Human.

Innocent Traveler

At the beginning of your upkeep, any opponent may sacrifice a creature of their choice. If no one does, transform this creature.

Innocent Traveler // Malicious Invader

Chartooth Cougar

{R}: This creature gets +1/+0 until end of turn.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Aspect of Lamprey

Enchant creature you control
When this Aura enters, target opponent discards two cards.
Enchanted creature has lifelink.

Demon of Catastrophes

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

Cavern Whisperer

Mutate {3}{B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Menace (This creature can't be blocked except by two or more creatures.)
Whenever this creature mutates, each opponent discards a card.

Fiery Finish

Fiery Finish deals 7 damage to target creature.

Murder

Expedite

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

Rift Bolt

Rift Bolt deals 3 damage to any target.
Suspend 1—{R} (Rather than cast this card from your hand, you may pay {R} and exile it with a time counter on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Mark of the Vampire

Enchant creature
Enchanted creature gets +2/+2 and has lifelink.

Renegade Demon

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Wall of Fire

Defender (This creature can't attack.)
{R}: This creature gets +1/+0 until end of turn.

Will-o'-the-Wisp

Flying (This creature can't be blocked except by creatures with flying or reach.)
{B}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Fire Prophecy

Fire Prophecy deals 3 damage to target creature. You may put a card from your hand on the bottom of your library. If you do, draw a card.

Consume Spirit

Spend only black mana on X.
Consume Spirit deals X damage to any target and you gain X life.

Lava Serpent

Haste
Cycling {2} ({2}, Discard this card: Draw a card.)

Profane Transfusion

Two target players exchange life totals. You create an X/X colorless Horror artifact creature token, where X is the difference between those players' life totals.

Boot Nipper

This creature enters with your choice of a deathtouch counter or a lifelink counter on it.

Volcanic Geyser

Volcanic Geyser deals X damage to any target.

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Agonizing Demise

Kicker {1}{R} (You may pay an additional {1}{R} as you cast this spell.)
Destroy target nonblack creature. It can't be regenerated. If this spell was kicked, Agonizing Demise deals damage equal to that creature's power to the creature's controller.