Feed the Serpent

Eradicator Valkyrie

Flying, lifelink, hexproof from planeswalkers
Boast — {1}{B}, Sacrifice a creature: Each opponent sacrifices a creature or planeswalker. (Activate only if this creature attacked this turn and only once each turn.)

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Promise of Power

Choose one —
• You draw five cards and you lose 5 life.
• Create an X/X black Demon creature token with flying, where X is the number of cards in your hand.
Entwine {4} (Choose both if you pay the entwine cost.)

Crypt Rats

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

Unlikely Aid

Target creature gets +2/+0 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Blood Beckoning

Kicker {3} (You may pay an additional {3} as you cast this spell.)
Return target creature card from your graveyard to your hand. If this spell was kicked, instead return two target creature cards from your graveyard to your hand.

Throat Slitter

Ninjutsu {2}{B} ({2}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Throat Slitter deals combat damage to a player, destroy target nonblack creature that player controls.

Hooded Blightfang

Deathtouch
Whenever a creature you control with deathtouch attacks, each opponent loses 1 life and you gain 1 life.
Whenever a creature you control with deathtouch deals damage to a planeswalker, destroy that planeswalker.

Marrow-Gnawer

All Rats have fear.
{T}, Sacrifice a Rat: Create X 1/1 black Rat creature tokens, where X is the number of Rats you control.

Sinuous Vermin

{3}{B}{B}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
As long as Sinuous Vermin is monstrous, it has menace. (It can't be blocked except by two or more creatures.)

Spark Harvest

As an additional cost to cast this spell, sacrifice a creature or pay {3}{B}.
Destroy target creature or planeswalker.

Radiant Fountain

When Radiant Fountain enters, you gain 2 life.
{T}: Add {C}.

Unholy Indenture

Enchant creature
When enchanted creature dies, return that card to the battlefield under your control with a +1/+1 counter on it.

Oblivion's Hunger

Target creature you control gains indestructible until end of turn. Draw a card if that creature has a +1/+1 counter on it. (Damage and effects that say "destroy" don't destroy the creature.)

Greed

Traveler's Amulet

{1}, Sacrifice Traveler's Amulet: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Ogre Slumlord

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.
Rats you control have deathtouch.

Witch's Cottage

({T}: Add {B}.)
Witch's Cottage enters tapped unless you control three or more other Swamps.
When Witch's Cottage enters untapped, you may put target creature card from your graveyard on top of your library.

Patron of the Nezumi

Rat offering (You may cast this spell any time you could cast an instant by sacrificing a Rat and paying the difference in mana costs between this and the sacrificed Rat. Mana cost includes color.)
Whenever a permanent is put into an opponent's graveyard, that player loses 1 life.

Sol Ring

Palladium Myr

Species Specialist

As Species Specialist enters, choose a creature type.
Whenever a creature of the chosen type dies, you may draw a card.

Burnished Hart

{3}, Sacrifice this creature: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Thran Dynamo

Skemfar Shadowsage

When Skemfar Shadowsage enters, choose one —
• Each opponent loses X life, where X is the greatest number of creatures you control that have a creature type in common.
• You gain X life, where X is the greatest number of creatures you control that have a creature type in common.

Piper of the Swarm

Rats you control have menace.
{1}{B}, {T}: Create a 1/1 black Rat creature token.
{2}{B}{B}, {T}, Sacrifice three Rats: Gain control of target creature.

Stronghold Rats

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Stronghold Rats deals combat damage to a player, each player discards a card.

Relentless Rats

Relentless Rats gets +1/+1 for each other creature on the battlefield named Relentless Rats.
A deck can have any number of cards named Relentless Rats.

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Swarm of Rats

Swarm of Rats's power is equal to the number of Rats you control.

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Swamp

Burglar Rat

When this creature enters, each opponent discards a card.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Funeral Rites

You draw two cards, lose 2 life, then mill two cards.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Zof Bloodbog

Zof Bloodbog enters tapped.
{T}: Add {B}.

Zof Consumption

Each opponent loses 4 life and you gain 4 life.

Zof Consumption // Zof Bloodbog

Lampad of Death's Vigil

{1}, Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.

Rotting Rats

When Rotting Rats enters, each player discards a card.
Unearth {1}{B} ({1}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Pestilence Rats

Pestilence Rats's power is equal to the number of other Rats on the battlefield. (For example, as long as there are two other Rats on the battlefield, Pestilence Rats's power and toughness are 2/3.)

Foreboding Fruit

Target player draws two cards and loses 2 life.
Adamant — If at least three black mana was spent to cast this spell, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Ob Nixilis's Cruelty

Target creature gets -5/-5 until end of turn. If that creature would die this turn, exile it instead.

Ambition's Cost

You draw three cards and you lose 3 life.

Ob Nixilis, the Hate-Twisted

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

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Raise the Draugr

Choose one —
• Return target creature card from your graveyard to your hand.
• Return two target creature cards that share a creature type from your graveyard to your hand.

Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
Everflowing Chalice enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on Everflowing Chalice.

Bastion of Remembrance

When Bastion of Remembrance enters, create a 1/1 white Human Soldier creature token.
Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.

Tergrid's Shadow

Each player sacrifices two creatures.
Foretell {2}{B}{B} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Witch's Cauldron

{1}{B}, {T}, Sacrifice a creature: You gain 1 life and draw a card.

Worn Powerstone

Worn Powerstone enters tapped.
{T}: Add {C}{C}.

Bushmeat Poacher

{1}, {T}, Sacrifice another creature: You gain life equal to the sacrificed creature's toughness. Draw a card.

Dread Presence

Whenever a Swamp you control enters, choose one —
• You draw a card and you lose 1 life.
• Dread Presence deals 2 damage to any target and you gain 2 life.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Dark Bargain

Look at the top three cards of your library. Put two of them into your hand and the other into your graveyard. Dark Bargain deals 2 damage to you.

Bontu's Monument

Black creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, each opponent loses 1 life and you gain 1 life.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Pack Rat

Pack Rat's power and toughness are each equal to the number of Rats you control.
{2}{B}, Discard a card: Create a token that's a copy of Pack Rat.