Mephitic Vapors

All creatures get -1/-1 until end of turn.
Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Gnat Miser

Each opponent's maximum hand size is reduced by one.

Necrotic Hex

Each player sacrifices six creatures. You create six tapped 2/2 black Zombie creature tokens.

Mudflat Village

{T}: Add {C}.
{T}: Add {B}. Spend this mana only to cast a creature spell.
{1}{B}, {T}, Sacrifice Mudflat Village: Return target Bat, Lizard, Rat, or Squirrel card from your graveyard to your hand.

Shell Shield

Kicker {1} (You may pay an additional {1} as you cast this spell.)
Target creature you control gets +0/+3 until end of turn. If this spell was kicked, that creature also gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Make Obsolete

Creatures your opponents control get -1/-1 until end of turn.

Undying Evil

Target creature gains undying until end of turn. (When it dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Submerged Boneyard

Submerged Boneyard enters tapped.
{T}: Add {U} or {B}.

Waterfront District

Waterfront District enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}, {T}, Sacrifice Waterfront District: Draw a card.

Charcoal Diamond

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

Mind Drill Assailant

Threshold — As long as seven or more cards are in your graveyard, Mind Drill Assailant gets +3/+0.
{2}{U/B}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Fleshbag Marauder

When Fleshbag Marauder enters, each player sacrifices a creature.

Cloudkill

All creatures get -X/-X until end of turn, where X is the greatest mana value of a commander you own on the battlefield or in the command zone.

Dimir Locket

{T}: Add {U} or {B}.
{U/B}{U/B}{U/B}{U/B}, {T}, Sacrifice Dimir Locket: Draw two cards.

Persistent Marshstalker

Persistent Marshstalker gets +1/+0 for each other Rat you control.
Threshold — Whenever you attack with one or more Rats, if seven or more cards are in your graveyard, you may pay {2}{B}. If you do, return Persistent Marshstalker from your graveyard to the battlefield tapped and attacking.

Darkwater Catacombs

Soul Manipulation

Choose one or both —
• Counter target creature spell.
• Return target creature card from your graveyard to your hand.

Island

Dive Down

Target creature you control gets +0/+3 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Sign in Blood

Target player draws two cards and loses 2 life.

Shriveling Rot

Choose one —
• Until end of turn, whenever a creature is dealt damage, destroy it.
• Until end of turn, whenever a creature dies, that creature's controller loses life equal to its toughness.
Entwine {2}{B} (Choose both if you pay the entwine cost.)

Bladebrand

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

Disentomb

Return target creature card from your graveyard to your hand.

Infest

All creatures get -2/-2 until end of turn.

Witch-king of Angmar

Flying
Whenever one or more creatures deal combat damage to you, each opponent sacrifices a creature that dealt combat damage to you this turn. The Ring tempts you.
Discard a card: Witch-king of Angmar gains indestructible until end of turn. Tap it.

Grixis Panorama

{T}: Add {C}.
{1}, {T}, Sacrifice Grixis Panorama: Search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Doom Blade

Cast Down

Vendetta

Destroy target nonblack creature. It can't be regenerated. You lose life equal to that creature's toughness.

Sever the Bloodline

Exile target creature and all other creatures with the same name as that creature.
Flashback {5}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Liliana's Triumph

Each opponent sacrifices a creature. If you control a Liliana planeswalker, each opponent also discards a card.

Tidecaller Mentor

Menace
Threshold — When Tidecaller Mentor enters, if seven or more cards are in your graveyard, return up to one target nonland permanent to its owner's hand.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Fake Your Own Death

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control and you create a Treasure token." (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

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.

Flash Counter

Shrivel

All creatures get -1/-1 until end of turn.

Flaying Tendrils

Devoid (This card has no color.)
All creatures get -2/-2 until end of turn. If a creature would die this turn, exile it instead.

Kaervek, the Spiteful

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Vren, the Relentless

Ward {2}
If a creature an opponent controls would die, exile it instead.
At the beginning of each end step, create X 1/1 black Rat creature tokens with "This creature gets +1/+1 for each other Rat you control," where X is the number of creatures your opponents controlled that were exiled this turn.

Shore Up

Target creature you control gets +1/+1 and gains hexproof until end of turn. Untap it. (It can't be the target of spells or abilities your opponents control.)

Accursed Marauder

When Accursed Marauder enters, each player sacrifices a nontoken creature.

Thought Shucker

Threshold — {1}{U}: Put a +1/+1 counter on Thought Shucker and draw a card. Activate only if seven or more cards are in your graveyard and only once.

Dismal Backwater

Dismal Backwater enters tapped.
When Dismal Backwater enters, you gain 1 life.
{T}: Add {U} or {B}.

Dimir Guildgate

Dimir Guildgate enters tapped.
{T}: Add {U} or {B}.

Remove Soul

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

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.

Negate

Village Rites

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

Tyrant's Scorn

Choose one —
• Destroy target creature with mana value 3 or less.
• Return target creature to its owner's hand.

Temple of Deceit

Temple of Deceit enters tapped.
When Temple of Deceit enters, scry 1.
{T}: Add {U} or {B}.

Lord Skitter's Butcher

When Lord Skitter's Butcher enters, choose one —
• Create a 1/1 black Rat creature token with "This creature can't block."
• You may sacrifice another creature. If you do, scry 2, then draw a card.
• Creatures you control gain menace until end of turn.

Sol Ring

Echo of Death's Wail

Flying, haste
When Echo of Death's Wail enters, gain control of all Rat tokens.
Whenever Echo of Death's Wail attacks, you may sacrifice another creature. If you do, draw a card.

Tribute to Horobi

(As this Saga enters and after your draw step, add a lore counter.)
I, II — Each opponent creates a 1/1 black Rat Rogue creature token.
III — Exile this Saga, then return it to the battlefield transformed under your control.

Tribute to Horobi // Echo of Death's Wail

Unlikely Aid

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

Golden Demise

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
All creatures get -2/-2 until end of turn. If you have the city's blessing, instead only creatures your opponents control get -2/-2 until end of turn.

Swamp

River of Tears

{T}: Add {U}. If you played a land this turn, add {B} instead.

Ogre Slumlord

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

Wail of the Nim

Choose one —
• Regenerate each creature you control.
• Wail of the Nim deals 1 damage to each creature and each player.
Entwine {B} (Choose both if you pay the entwine cost.)

Barter in Blood

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Kor Dirge

All damage that would be dealt this turn to target creature you control by a source of your choice is dealt to another target creature instead.

Merciless Executioner

When Merciless Executioner enters, each player sacrifices a creature.

Typhoid Rats

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Murder

Dimir Cluestone

{T}: Add {U} or {B}.
{U}{B}, {T}, Sacrifice Dimir Cluestone: Draw a card.

Mana Leak

Counter target spell unless its controller pays {3}.

Rancid Rats

Skulk (This creature can't be blocked by creatures with greater power.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Supernatural Stamina

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Arcane Signet

Demon's Disciple

When Demon's Disciple enters, each player sacrifices a creature or planeswalker.