Rakdos Signet

Blur of Blades

Put a -1/-1 counter on target creature. Blur of Blades deals 2 damage to that creature's controller.

Expunge

Destroy target nonartifact, nonblack creature. It can't be regenerated.
Cycling {2} ({2}, Discard this card: Draw a card.)

Shadows of the Past

Whenever a creature dies, scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)
{4}{B}: Each opponent loses 2 life and you gain 2 life. Activate only if there are four or more creature cards in your graveyard.

Grim Affliction

Put a -1/-1 counter on target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Instill Infection

Put a -1/-1 counter on target creature.
Draw a card.

Banewhip Punisher

When Banewhip Punisher enters the battlefield, you may put a -1/-1 counter on target creature.
{B}, Sacrifice Banewhip Punisher: Destroy target creature that has a -1/-1 counter on it.

Contagion Clasp

When Contagion Clasp enters the battlefield, put a -1/-1 counter on target creature.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Scrap

Destroy target artifact.
Cycling {2} ({2}, Discard this card: Draw a card.)

Merciless Javelineer

{2}, Discard a card: Put a -1/-1 counter on target creature. That creature can't block this turn.

Spread the Sickness

Destroy target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Archfiend of Ifnir

Flying
Whenever you cycle or discard another card, put a -1/-1 counter on each creature your opponents control.
Cycling {2} ({2}, Discard this card: Draw a card.)

Puncture Bolt

Puncture Bolt deals 1 damage to target creature. Put a -1/-1 counter on that creature.

Yidaro, Wandering Monster

Trample, haste
Cycling {1}{R}
When you cycle Yidaro, Wandering Monster, shuffle it into your library from your graveyard. If you've cycled a card named Yidaro, Wandering Monster four or more times this game, put it onto the battlefield from your graveyard instead. (Do this before you draw.)

Black Market

Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your precombat main phase, add {B} for each charge counter on Black Market.

Baleful Ammit

Lifelink
When Baleful Ammit enters the battlefield, put a -1/-1 counter on target creature you control.

Shredded Sails

Choose one —
• Destroy target artifact.
• Shredded Sails deals 4 damage to target creature with flying.
Cycling {2} ({2}, Discard this card: Draw a card.)

Canyon Slough

({T}: Add {B} or {R}.)
Canyon Slough enters the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Blowfly Infestation

Whenever a creature dies, if it had a -1/-1 counter on it, put a -1/-1 counter on target creature.

Incremental Blight

Put a -1/-1 counter on target creature, two -1/-1 counters on another target creature, and three -1/-1 counters on a third target creature.

Soul Snuffers

When Soul Snuffers enters the battlefield, put a -1/-1 counter on each creature.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Contagion Engine

When Contagion Engine enters the battlefield, put a -1/-1 counter on each creature target player controls.
{4}, {T}: Proliferate twice. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

Trigon of Corruption

Trigon of Corruption enters the battlefield with three charge counters on it.
{B}{B}, {T}: Put a charge counter on Trigon of Corruption.
{2}, {T}, Remove a charge counter from Trigon of Corruption: Put a -1/-1 counter on target creature.

Hateflayer

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{2}{R}, {Q}: Hateflayer deals damage equal to its power to any target. ({Q} is the untap symbol.)

Drannith Stinger

Whenever you cycle another card, Drannith Stinger deals 1 damage to each opponent.
Cycling {1} ({1}, Discard this card: Draw a card.)

Soulstinger

When Soulstinger enters the battlefield, put two -1/-1 counters on target creature you control.
When Soulstinger dies, you may put a -1/-1 counter on target creature for each -1/-1 counter on Soulstinger.

Grief Tyrant

Grief Tyrant enters the battlefield with four -1/-1 counters on it.
When Grief Tyrant dies, put a -1/-1 counter on target creature for each -1/-1 counter on Grief Tyrant.

Easy Prey

Destroy target creature with mana value 2 or less.
Cycling {2} ({2}, Discard this card: Draw a card.)

Manticore of the Gauntlet

When Manticore of the Gauntlet enters the battlefield, put a -1/-1 counter on target creature you control. Manticore of the Gauntlet deals 3 damage to target opponent or planeswalker.

Karn's Bastion

{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Serrated Arrows

Serrated Arrows enters the battlefield with three arrowhead counters on it.
At the beginning of your upkeep, if there are no arrowhead counters on Serrated Arrows, sacrifice it.
{T}, Remove an arrowhead counter from Serrated Arrows: Put a -1/-1 counter on target creature.

Without Weakness

Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it. If its toughness is 0 or less, it's still put into its owner's graveyard.)
Cycling {2} ({2}, Discard this card: Draw a card.)

Midnight Banshee

Wither (This deals damage to creatures in the form of -1/-1 counters.)
At the beginning of your upkeep, put a -1/-1 counter on each nonblack creature.

Glistening Oil

Enchant creature
Enchanted creature has infect.
At the beginning of your upkeep, put a -1/-1 counter on enchanted creature.
When Glistening Oil is put into a graveyard from the battlefield, return Glistening Oil to its owner's hand.

Ruthless Sniper

Whenever you cycle or discard a card, you may pay {1}. If you do, put a -1/-1 counter on target creature.

Lethal Sting

As an additional cost to cast this spell, put a -1/-1 counter on a creature you control.
Destroy target creature.

Sadistic Obsession

Enchant creature
Enchanted creature has "{B}, {T}: Put a -1/-1 counter on target creature."

Tectonic Reformation

Each land card in your hand has cycling {R}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Ammit Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
Whenever an opponent casts a spell, put a -1/-1 counter on Ammit Eternal.
Whenever Ammit Eternal deals combat damage to a player, remove all -1/-1 counters from it.

Scar

Festering Mummy

When Festering Mummy dies, you may put a -1/-1 counter on target creature.

Fume Spitter

Sacrifice Fume Spitter: Put a -1/-1 counter on target creature.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

The Scorpion God

Whenever a creature with a -1/-1 counter on it dies, draw a card.
{1}{B}{R}: Put a -1/-1 counter on another target creature.
When The Scorpion God dies, return it to its owner's hand at the beginning of the next end step.

Volt Charge

Volt Charge deals 3 damage to any target. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)