Chasm Skulker

Whenever you draw a card, put a +1/+1 counter on this creature.
When this creature dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on this creature. (They can't be blocked as long as defending player controls an Island.)

Genesis Chamber

Whenever a nontoken creature enters, if this artifact is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Fuel for the Cause

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

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Commander's Sphere

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

Infernal Grasp

Destroy target creature. You lose 2 life.

Notion Thief

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead that player skips that draw and you draw a card.

Turn to Frog

Until end of turn, target creature loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Plague Myr

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{T}: Add {C}.

Sludge Monster

Whenever this creature enters or attacks, put a slime counter on up to one other target creature.
Non-Horror creatures with slime counters on them lose all abilities and have base power and toughness 2/2.

Plumb the Forbidden

As an additional cost to cast this spell, you may sacrifice one or more creatures. When you do, copy this spell for each creature sacrificed this way.
You draw a card and you lose 1 life.

Mistvault Bridge

This land enters tapped.
Indestructible
{T}: Add {U} or {B}.

Swamp

Deepglow Skate

When this creature enters, double the number of each kind of counter on any number of target permanents.

Gisa, Glorious Resurrector

If a creature an opponent controls would die, exile it instead.
At the beginning of your upkeep, put all creature cards exiled with Gisa onto the battlefield under your control. They gain decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Ashiok, Dream Render

Spells and abilities your opponents control can't cause their controller to search their library.
−1: Target player mills four cards. Then exile each opponent's graveyard.

Dimir Signet

Hand of the Praetors

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Other creatures you control with infect get +1/+1.
Whenever you cast a creature spell with infect, target player gets a poison counter.

Dimir Guildgate

This land enters tapped.
{T}: Add {U} or {B}.

Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Go for the Throat

Temple of Deceit

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {U} or {B}.

Reaper of Sheoldred

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever a source deals damage to this creature, that source's controller gets a poison counter.

Sol Ring

Countersquall

Counter target noncreature spell. Its controller loses 2 life.

Dimir Cluestone

{T}: Add {U} or {B}.
{U}{B}, {T}, Sacrifice this artifact: Draw a card.

Mystic Sanctuary

({T}: Add {U}.)
This land enters tapped unless you control three or more other Islands.
When this land enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Victimize

Choose two target creature cards in your graveyard. Sacrifice a creature. If you do, return the chosen cards to the battlefield tapped.

Species Specialist

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

Arcane Signet

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

Island

Dark Privilege

Enchant creature
Enchanted creature gets +1/+1.
Sacrifice a creature: Regenerate enchanted creature.

Flux Channeler

Whenever you cast a noncreature spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Polymorphist's Jest

Until end of turn, each creature target player controls loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Yahenni, Undying Partisan

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni.
Sacrifice another creature: Yahenni gains indestructible until end of turn.

Inexorable Tide

Whenever you cast a spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Deprive

As an additional cost to cast this spell, return a land you control to its owner's hand.
Counter target spell.

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Wishclaw Talisman

This artifact enters with three wish counters on it.
{1}, {T}, Remove a wish counter from this artifact: Search your library for a card, put it into your hand, then shuffle. An opponent gains control of this artifact. Activate only during your turn.

Negate

Eloise, Nephalia Sleuth

Whenever another creature you control dies, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you sacrifice a token, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Mass Diminish

Until your next turn, creatures target player controls have base power and toughness 1/1.
Flashback {3}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Black Market

Whenever a creature dies, put a charge counter on this enchantment.
At the beginning of your first main phase, add {B} for each charge counter on this enchantment.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Blighted Agent

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
This creature can't be blocked.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Vedalken Humiliator

Metalcraft — Whenever this creature attacks, if you control three or more artifacts, creatures your opponents control lose all abilities and have base power and toughness 1/1 until end of turn.

Ayara, First of Locthwain

Whenever Ayara or another black creature you control enters, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: 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.

Steady Progress

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Sunken Hollow

({T}: Add {U} or {B}.)
This land enters tapped unless you control two or more basic lands.

Awaken the Erstwhile

Each player discards all the cards in their hand, then creates that many 2/2 black Zombie creature tokens.

Ashnod's Altar

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Command Tower

Reliquary Tower

Crypt Ghast

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever you tap a Swamp for mana, add an additional {B}.

Phyrexian Digester

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Dreadship Reef

{T}: Add {C}.
{1}, {T}: Put a storage counter on this land.
{1}, Remove X storage counters from this land: Add X mana in any combination of {U} and/or {B}.

Darkwater Catacombs

Toxrill, the Corrosive

At the beginning of each end step, put a slime counter on each creature you don't control.
Creatures you don't control get -1/-1 for each slime counter on them.
Whenever a creature you don't control with a slime counter on it dies, create a 1/1 black Slug creature token.
{U}{B}, Sacrifice a Slug: Draw a card.

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.)

Jace Beleren

+2: Each player draws a card.
−1: Target player draws a card.
−10: Target player mills twenty cards.

Everflowing Chalice

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

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Gift of Doom

Enchant creature
Enchanted creature has deathtouch and indestructible.
Morph—Sacrifice another creature. (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
As this Aura is turned face up, you may attach it to a creature.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

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.)

Thrummingbird

Flying
Whenever this creature deals combat damage to a player, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Harvester of Souls

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever another nontoken creature dies, you may draw a card.

Ogre Slumlord

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

Contentious Plan

Viral Drake

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Lost Vale

(Transforms from Dowsing Dagger.)
{T}: Add three mana of any one color.

Dowsing Dagger

When this Equipment enters, target opponent creates two 0/2 green Plant creature tokens with defender.
Equipped creature gets +2/+1.
Whenever equipped creature deals combat damage to a player, you may transform this Equipment.
Equip {2}

Dowsing Dagger // Lost Vale

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.)

Contagion Engine

When this artifact enters, 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.)

Feed the Swarm

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

Kels, Fight Fixer

Menace
Whenever you sacrifice a creature, you may pay {U/B}. If you do, draw a card. ({U/B} can be paid with either {U} or {B}.)
{1}, Sacrifice a creature: Kels gains indestructible until end of turn.

Village Rites

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

Flesh-Eater Imp

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Sacrifice a creature: Flesh-Eater Imp gets +1/+1 until end of turn.

Guildpact Informant

Flying
Whenever this creature deals combat damage to a player or planeswalker, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Ichor Rats

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When this creature enters, each player gets a poison counter.

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.)