Arcane Signet

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

Spreading Plague

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

Undercity Plague

Target player loses 1 life, discards a card, then sacrifices a permanent of their choice.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Plague Beetle

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Mistform Mask

Enchant creature
{1}: Enchanted creature becomes the creature type of your choice until end of turn.

Plague Fiend

Whenever Plague Fiend deals combat damage to a creature, destroy that creature unless its controller pays {2}.

Endemic Plague

As an additional cost to cast this spell, sacrifice a creature.
Destroy all creatures that share a creature type with the sacrificed creature. They can't be regenerated.

Plague Dogs

When Plague Dogs dies, all creatures get -1/-1 until end of turn.
{2}, Sacrifice Plague Dogs: Draw a card.

Plague Engineer

Deathtouch
As Plague Engineer enters, choose a creature type.
Creatures of the chosen type your opponents control get -1/-1.

Eternal Isolation

Put target creature with power 4 or greater on the bottom of its owner's library.

Mask of Riddles

Equipped creature has fear. (It can't be blocked except by artifact creatures and/or black creatures.)
Whenever equipped creature deals combat damage to a player, you may draw a card.
Equip {2}

Uba Mask

If a player would draw a card, that player exiles that card face up instead.
Each player may play lands and cast spells from among cards they exiled with Uba Mask this turn.

Quarantine Field

Quarantine Field enters with X isolation counters on it.
When Quarantine Field enters, for each isolation counter on it, exile up to one target nonland permanent an opponent controls until Quarantine Field leaves the battlefield.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Ivory Mask

You have shroud. (You can't be the target of spells or abilities.)

Plaguebearer

{X}{X}{B}: Destroy target nonblack creature with mana value X.

Temporal Isolation

Flash
Enchant creature
Enchanted creature has shadow. (It can block or be blocked by only creatures with shadow.)
Prevent all damage that would be dealt by enchanted creature.

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.)

Unmask

You may exile a black card from your hand rather than pay this spell's mana cost.
Target player reveals their hand. You choose a nonland card from it. That player discards that card.

Disease Carriers

When Disease Carriers dies, target creature gets -2/-2 until end of turn.

Quag Sickness

Enchant creature
Enchanted creature gets -1/-1 for each Swamp you control.

Engineered Plague

As Engineered Plague enters, choose a creature type.
All creatures of the chosen type get -1/-1.

Mask of Avacyn

Equipped creature gets +1/+2 and has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {3}

Deathmask Nezumi

As long as you have seven or more cards in hand, Deathmask Nezumi gets +2/+1 and has fear. (It can't be blocked except by artifact creatures and/or black creatures.)

Plague Spores

Destroy target nonblack creature and target land. They can't be regenerated.

Plagued Rusalka

{B}, Sacrifice a creature: Target creature gets -1/-1 until end of turn.

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker of their choice. Each player who can't discards a card.

Void Beckoner

Deathtouch
Cycling {2}{B} ({2}{B}, Discard this card: Draw a card.)
When you cycle Void Beckoner, put a deathtouch counter on target creature you control.

Plague Wind

Destroy all creatures you don't control. They can't be regenerated.

Plague Belcher

Menace
When Plague Belcher enters, put two -1/-1 counters on target creature you control.
Whenever another Zombie you control dies, each opponent loses 1 life.

Isolation Zone

When Isolation Zone enters, exile target creature or enchantment an opponent controls until Isolation Zone leaves the battlefield. (That permanent returns under its owner's control.)

Isolated Chapel

Isolated Chapel enters tapped unless you control a Plains or a Swamp.
{T}: Add {W} or {B}.

Agent of Masks

At the beginning of your upkeep, each opponent loses 1 life. You gain life equal to the life lost this way.

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.

Isolate

Exile target permanent with mana value 1.

Estrid, the Masked

+2: Untap each enchanted permanent you control.
−1: Create a white Aura enchantment token named Mask attached to another target permanent. The token has enchant permanent and umbra armor.
−7: Mill seven cards. Return all non-Aura enchantment cards from your graveyard to the battlefield, then do the same for Aura cards.
Estrid, the Masked can be your commander.

Sol Ring

Karona, False God

Haste
At the beginning of each player's upkeep, that player untaps Karona, False God and gains control of it.
Whenever Karona attacks, creatures of the creature type of your choice get +3/+3 until end of turn.

Isolated Watchtower

{T}: Add {C}.
{2}, {T}: Scry 1, then you may reveal the top card of your library. If a basic land card is revealed this way, put it onto the battlefield tapped. Activate only if an opponent controls at least two more lands than you.

Strength of Isolation

Enchant creature
Enchanted creature gets +1/+2 and has protection from black.
Madness {W} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Karona's Zealot

Morph {3}{W}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Karona's Zealot is turned face up, all damage that would be dealt to it this turn is dealt to target creature instead.

Peregrine Mask

Equipped creature has defender, flying, and first strike.
Equip {2}

Virulent Plague

Farsight Mask

Whenever a source an opponent controls deals damage to you, if Farsight Mask is untapped, you may draw a card.

Necrotic Plague

Enchant creature
Enchanted creature has "At the beginning of your upkeep, sacrifice this creature."
When enchanted creature dies, its controller chooses target creature one of their opponents controls. Return Necrotic Plague from its owner's graveyard to the battlefield attached to that creature.

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Garza Zol, Plague Queen

Flying, haste
Whenever a creature dealt damage by Garza Zol, Plague Queen this turn dies, put a +1/+1 counter on Garza Zol.
Whenever Garza Zol deals combat damage to a player, you may draw a card.

Masked Admirers

When Masked Admirers enters, draw a card.
Whenever you cast a creature spell, you may pay {G}{G}. If you do, return Masked Admirers from your graveyard to your hand.

Desecration Plague

Mask of Intolerance

At the beginning of each player's upkeep, if there are four or more basic land types among lands that player controls, Mask of Intolerance deals 3 damage to that player.

Kelsien, the Plague

Vigilance, haste
Kelsien, the Plague gets +1/+1 for each experience counter you have.
{T}: Kelsien deals 1 damage to target creature you don't control. When that creature dies this turn, you get an experience counter.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Outbreak

You may discard a Swamp card rather than pay this spell's mana cost.
Choose a creature type. All creatures of that type get -1/-1 until end of turn.

Mask of Immolation

When Mask of Immolation enters, create a 1/1 red Elemental creature token, then attach Mask of Immolation to it.
Equipped creature has "Sacrifice this creature: It deals 1 damage to any target."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Mask of Memory

Whenever equipped creature deals combat damage to a player, you may draw two cards. If you do, discard a card.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Dakmor Plague

Dakmor Plague deals 3 damage to each creature and each player.

Plague Mare

Plague Mare can't be blocked by white creatures.
When Plague Mare enters, creatures your opponents control get -1/-1 until end of turn.

Swallowing Plague

Swallowing Plague deals X damage to target creature and you gain X life.

Mask of the Mimic

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a card with the same name as target nontoken creature, put that card onto the battlefield, then shuffle.

Nemesis Mask

All creatures able to block equipped creature do so.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Mask of Law and Grace

Enchant creature
Enchanted creature has protection from black and from red.

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}.

Phyrexian Plaguelord

{T}, Sacrifice Phyrexian Plaguelord: Target creature gets -4/-4 until end of turn.
Sacrifice a creature: Target creature gets -1/-1 until end of turn.

Exotic Disease

Domain — Target player loses X life and you gain X life, where X is the number of basic land types among lands you control.

Plague Boiler

At the beginning of your upkeep, put a plague counter on Plague Boiler.
{1}{B}{G}: Put a plague counter on Plague Boiler or remove a plague counter from it.
When Plague Boiler has three or more plague counters on it, sacrifice it. If you do, destroy all nonland permanents.