Nightshade Seer

{2}{B}, {T}: Reveal any number of black cards in your hand. Target creature gets -X/-X until end of turn, where X is the number of cards revealed this way.

Sheoldred, Whispering One

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.
At the beginning of each opponent's upkeep, that player sacrifices a creature of their choice.

Krovikan Sorcerer

{T}, Discard a nonblack card: Draw a card.
{T}, Discard a black card: Draw two cards, then discard one of them.

Well-Laid Plans

Prevent all damage that would be dealt to a creature by another creature if they share a color.

Hall of Triumph

As Hall of Triumph enters, choose a color.
Creatures you control of the chosen color get +1/+1.

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Faerie Swarm

Flying
Faerie Swarm's power and toughness are each equal to the number of blue permanents you control.

Sword of Feast and Famine

Equipped creature gets +2/+2 and has protection from black and from green.
Whenever equipped creature deals combat damage to a player, that player discards a card and you untap all lands you control.
Equip {2}

Filth

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
As long as Filth is in your graveyard and you control a Swamp, creatures you control have swampwalk.

Flow of Ideas

Spreading Seas

Enchant land
When Spreading Seas enters, draw a card.
Enchanted land is an Island.

Defile

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

Seasinger

When you control no Islands, sacrifice Seasinger.
You may choose not to untap Seasinger during your untap step.
{T}: Gain control of target creature whose controller controls an Island for as long as you control Seasinger and Seasinger remains tapped.

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.

Mystical Dispute

This spell costs {2} less to cast if it targets a blue spell.
Counter target spell unless its controller pays {3}.

Nightmare Lash

Equipped creature gets +1/+1 for each Swamp you control.
Equip—Pay 3 life. (Pay 3 life: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Scuttlemutt

{T}: Add one mana of any color.
{T}: Target creature becomes the color or colors of your choice until end of turn.

Ugin, the Spirit Dragon

+2: Ugin, the Spirit Dragon deals 3 damage to any target.
−X: Exile each permanent with mana value X or less that's one or more colors.
−10: You gain 7 life, draw seven cards, then put up to seven permanent cards from your hand onto the battlefield.

Tsabo's Assassin

{T}: Destroy target creature if it shares a color with the most common color among all permanents or a color tied for most common. A creature destroyed this way can't be regenerated.

Corrupt

Corrupt deals damage to any target equal to the number of Swamps you control. You gain life equal to the damage dealt this way.

Jaded Response

Counter target spell if it shares a color with a creature you control.

Ashiok, Nightmare Muse

+1: Create a 2/3 blue and black Nightmare creature token with "Whenever this creature attacks or blocks, each opponent exiles the top two cards of their library."
−3: Return target nonland permanent to its owner's hand, then that player exiles a card from their hand.
−7: You may cast up to three spells from among face-up cards your opponents own from exile without paying their mana costs.

Sword of Light and Shadow

Equipped creature gets +2/+2 and has protection from white and from black.
Whenever equipped creature deals combat damage to a player, you gain 3 life and you may return up to one target creature card from your graveyard to your hand.
Equip {2}

Tribute Mage

When Tribute Mage enters, you may search your library for an artifact card with mana value 2, reveal that card, put it into your hand, then shuffle.

Strands of Night

{B}{B}, Pay 2 life, Sacrifice a Swamp: Return target creature card from your graveyard to the battlefield.

Tainted Well

Enchant land
When Tainted Well enters, draw a card.
Enchanted land is a Swamp.

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Spirit of the Night

Flying, trample, haste, protection from black
Spirit of the Night has first strike as long as it's attacking.

Darkest Hour

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Mana Maze

Players can't cast spells that share a color with the spell most recently cast this turn.

Vedalken Shackles

You may choose not to untap Vedalken Shackles during your untap step.
{2}, {T}: Gain control of target creature with power less than or equal to the number of Islands you control for as long as Vedalken Shackles remains tapped.

Magus of the Coffers

{2}, {T}: Add {B} for each Swamp you control.

Scourge of Fleets

When Scourge of Fleets enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Plague of Vermin

Starting with you, each player may pay any amount of life. Repeat this process until no one pays life. Each player creates a 1/1 black Rat creature token for each 1 life they paid this way.

Nirkana Revenant

Whenever you tap a Swamp for mana, add an additional {B}.
{B}: Nirkana Revenant gets +1/+1 until end of turn.

Ayara, First of Locthwain

Whenever Ayara, First of Locthwain 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.

Indigo Faerie

Flying
{U}: Target permanent becomes blue in addition to its other colors until end of turn.

Sway of Illusion

Any number of target creatures become the color of your choice until end of turn.
Draw a card.

Riptide

Oona, Queen of the Fae

Flying
{X}{U/B}: Choose a color. Target opponent exiles the top X cards of their library. For each card of the chosen color exiled this way, create a 1/1 blue and black Faerie Rogue creature token with flying.

Stormtide Leviathan

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.

Swirl the Mists

As Swirl the Mists enters, choose a color word.
All instances of color words in the text of spells and permanents are changed to the chosen color word.

Jace's Defeat

Counter target blue spell. If it was a Jace planeswalker spell, scry 2.

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.

Wrexial, the Risen Deep

Islandwalk, swampwalk (This creature can't be blocked as long as defending player controls an Island or a Swamp.)
Whenever Wrexial, the Risen Deep deals combat damage to a player, you may cast target instant or sorcery card from that player's graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Dire Undercurrents

Whenever a blue creature you control enters, you may have target player draw a card.
Whenever a black creature you control enters, you may have target player discard a card.

Vodalian Mystic

{T}: Target instant or sorcery spell becomes the color of your choice.

Liliana's Defeat

Destroy target black creature or black planeswalker. If that permanent was a Liliana planeswalker, her controller loses 3 life.

Thriving Isle

Thriving Isle enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Nim Deathmantle

Equipped creature gets +2/+2, has intimidate, and is a black Zombie. (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a nontoken creature is put into your graveyard from the battlefield, you may pay {4}. If you do, return that card to the battlefield and attach Nim Deathmantle to it.
Equip {4}

Kormus Bell

All Swamps are 1/1 black creatures that are still lands.

Blind Seer

{1}{U}: Target spell or permanent becomes the color of your choice until end of turn.

Repentant Vampire

Flying
Whenever a creature dealt damage by Repentant Vampire this turn dies, put a +1/+1 counter on Repentant Vampire.
Threshold — As long as seven or more cards are in your graveyard, Repentant Vampire is white and has "{T}: Destroy target black creature."

Thrull Wizard

{1}{B}: Counter target black spell unless that spell's controller pays {B} or {3}.

Llawan, Cephalid Empress

When Llawan, Cephalid Empress enters, return all blue creatures your opponents control to their owners' hands.
Your opponents can't cast blue creature spells.

Notorious Throng

Prowl {5}{U} (You may cast this for its prowl cost if you dealt combat damage to a player this turn with a Rogue.)
Create X 1/1 black Faerie Rogue creature tokens with flying, where X is the damage dealt to your opponents this turn. If this spell's prowl cost was paid, take an extra turn after this one.

Gainsay

Cyclopean Tomb

{2}, {T}: Put a mire counter on target non-Swamp land. That land is a Swamp for as long as it has a mire counter on it. Activate only during your upkeep.
When Cyclopean Tomb is put into a graveyard from the battlefield, at the beginning of each of your upkeeps for the rest of the game, remove all mire counters from a land that a mire counter was put onto with Cyclopean Tomb but that a mire counter has not been removed from with Cyclopean Tomb.

Bitterblossom

At the beginning of your upkeep, you lose 1 life and create a 1/1 black Faerie Rogue creature token with flying.

Psychic Allergy

As Psychic Allergy enters, choose a color.
At the beginning of each opponent's upkeep, Psychic Allergy deals X damage to that player, where X is the number of nontoken permanents of the chosen color they control.
At the beginning of your upkeep, destroy Psychic Allergy unless you sacrifice two Islands.

Glen Elendra Liege

Flying
Other blue creatures you control get +1/+1.
Other black creatures you control get +1/+1.

Fabricate

Search your library for an artifact card, reveal it, put it into your hand, then shuffle.

Metathran Transport

Flying
Metathran Transport can't be blocked by blue creatures.
{U}: Target creature becomes blue until end of turn.

Arcane Signet

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

Tidal Warrior

{T}: Target land becomes an Island until end of turn.

Cabal Coffers

Blanket of Night

Each land is a Swamp in addition to its other land types.

Korlash, Heir to Blackblade

Korlash, Heir to Blackblade's power and toughness are each equal to the number of Swamps you control.
{1}{B}: Regenerate Korlash.
Grandeur — Discard another card named Korlash, Heir to Blackblade: Search your library for up to two Swamp cards, put them onto the battlefield tapped, then shuffle.

Cackling Counterpart

Create a token that's a copy of target creature you control.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Ring of Xathrid

{2}: Regenerate equipped creature. (The next time that creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's black.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Glamerdye

Change the text of target spell or permanent by replacing all instances of one color word with another.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Lashwrithe

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 for each Swamp you control.
Equip {B/P}{B/P} ({B/P} can be paid with either {B} or 2 life.)

Vesuvan Doppelganger

You may have Vesuvan Doppelganger enter as a copy of any creature on the battlefield, except it doesn't copy that creature's color and it has "At the beginning of your upkeep, you may have this creature become a copy of target creature, except it doesn't copy that creature's color and it has this ability."

Sword of Fire and Ice

Equipped creature gets +2/+2 and has protection from red and from blue.
Whenever equipped creature deals combat damage to a player, Sword of Fire and Ice deals 2 damage to any target and you draw a card.
Equip {2}

Sphinx's Tutelage

Whenever you draw a card, target opponent mills two cards. If two nonland cards that share a color were milled this way, repeat this process.
{5}{U}: Draw a card, then discard a card.

Quicksilver Fountain

At the beginning of each player's upkeep, that player puts a flood counter on target non-Island land they control of their choice. That land is an Island for as long as it has a flood counter on it.
At the beginning of each end step, if all lands on the battlefield are Islands, remove all flood counters from them.

Sanctuary Blade

As Sanctuary Blade becomes attached to a creature, choose a color.
Equipped creature gets +2/+0 and has protection from the last chosen color.
Equip {3}

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Floodgate

Defender
When Floodgate has flying, sacrifice it.
When Floodgate leaves the battlefield, it deals damage to each nonblue creature without flying equal to half the number of Islands you control, rounded down.

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.

Sword of Body and Mind

Equipped creature gets +2/+2 and has protection from green and from blue.
Whenever equipped creature deals combat damage to a player, you create a 2/2 green Wolf creature token and that player mills ten cards.
Equip {2}

Thriving Moor

Thriving Moor enters tapped. As it enters, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Sword of Sinew and Steel

Equipped creature gets +2/+2 and has protection from black and from red.
Whenever equipped creature deals combat damage to a player, destroy up to one target planeswalker and up to one target artifact.
Equip {2}

Nightcreep

Until end of turn, all creatures become black and all lands become Swamps.

Sword of Truth and Justice

Equipped creature gets +2/+2 and has protection from white and from blue.
Whenever equipped creature deals combat damage to a player, put a +1/+1 counter on a creature you control, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Equip {2}

Trinket Mage

When Trinket Mage enters, you may search your library for an artifact card with mana value 1 or less, reveal that card, put it into your hand, then shuffle.

Spreading Plague

Whenever a creature enters, destroy all other creatures that share a color with it. They can't be regenerated.

Crowd of Cinders

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Crowd of Cinders's power and toughness are each equal to the number of black permanents you control.

Razorjaw Oni

Thada Adel, Acquisitor

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Thada Adel, Acquisitor deals combat damage to a player, search that player's library for an artifact card and exile it. Then that player shuffles. Until end of turn, you may play that card.

Persecute

Choose a color. Target player reveals their hand and discards all cards of that color.

Zombie Trailblazer

Tap an untapped Zombie you control: Target land becomes a Swamp until end of turn.
Tap an untapped Zombie you control: Target creature gains swampwalk until end of turn. (It can't be blocked as long as defending player controls a Swamp.)

Painter's Servant

As Painter's Servant enters, choose a color.
All cards that aren't on the battlefield, spells, and permanents are the chosen color in addition to their other colors.

Touch of Darkness

One or more target creatures become black until end of turn.

Demonic Tutor

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

Curse of Wizardry

As Curse of Wizardry enters, choose a color.
Whenever a player casts a spell of the chosen color, that player loses 1 life.

Wash Out

Return all permanents of the color of your choice to their owners' hands.

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}.

Jorubai Murk Lurker

Jorubai Murk Lurker gets +1/+1 as long as you control a Swamp.
{1}{B}: Target creature gains lifelink until end of turn. (Damage dealt by the creature also causes its controller to gain that much life.)

Paradise Plume

As Paradise Plume enters, choose a color.
Whenever a player casts a spell of the chosen color, you may gain 1 life.
{T}: Add one mana of the chosen color.

The Scarab God

At the beginning of your upkeep, each opponent loses X life and you scry X, where X is the number of Zombies you control.
{2}{U}{B}: Exile target creature card from a graveyard. Create a token that's a copy of it, except it's a 4/4 black Zombie.
When The Scarab God dies, return it to its owner's hand at the beginning of the next end step.

Ring of Evos Isle

{2}: Equipped creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's blue.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Scrying Glass

{3}, {T}: Choose a number greater than 0 and a color. Target opponent reveals their hand. If that opponent reveals exactly the chosen number of cards of the chosen color, you draw a card.