Ritual of Soot

Destroy all creatures with mana value 3 or less.

Severed Strands

As an additional cost to cast this spell, sacrifice a creature.
You gain life equal to the sacrificed creature's toughness. Destroy target creature an opponent controls.

Spinal Centipede

When this creature dies, put a +1/+1 counter on target creature you control.

Undercity Necrolisk

{1}, Sacrifice another creature: Put a +1/+1 counter on this creature. It gains menace until end of turn. Activate only as a sorcery. (It can't be blocked except by two or more creatures.)

Veiled Shade

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

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Demotion

Enchant creature
Enchanted creature can't block, and its activated abilities can't be activated.

Whispering Snitch

Whenever you surveil for the first time each turn, this creature deals 1 damage to each opponent and you gain 1 life.

Arclight Phoenix

Flying, haste
At the beginning of combat on your turn, if you've cast three or more instant and sorcery spells this turn, return this card from your graveyard to the battlefield.

Barging Sergeant

Haste
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Book Devourer

Trample
Whenever this creature deals combat damage to a player, you may discard all the cards in your hand. If you do, draw that many cards.

Command the Storm

Command the Storm deals 5 damage to target creature.

Cosmotronic Wave

Cosmotronic Wave deals 1 damage to each creature your opponents control. Creatures your opponents control can't block this turn.

Direct Current

Direct Current deals 2 damage to any target.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Electrostatic Field

Defender
Whenever you cast an instant or sorcery spell, this creature deals 1 damage to each opponent.

Erratic Cyclops

Trample
Whenever you cast an instant or sorcery spell, this creature gets +X/+0 until end of turn, where X is that spell's mana value.

Guilds of Ravnica