Door of Destinies

As Door of Destinies enters, choose a creature type.
Whenever you cast a spell of the chosen type, put a charge counter on Door of Destinies.
Creatures you control of the chosen type get +1/+1 for each charge counter on Door of Destinies.

Cruel Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Cryptic Gateway

Tap two untapped creatures you control: You may put a creature card from your hand that shares a creature type with each creature tapped this way onto the battlefield.

Black Market

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

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Thespian's Stage

{T}: Add {C}.
{2}, {T}: Thespian's Stage becomes a copy of target land, except it has this ability.

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.

Gilded Lotus

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Ambition's Cost

You draw three cards and you lose 3 life.

Plague Wind

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

Dark Petition

Search your library for a card, put that card into your hand, then shuffle.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, add {B}{B}{B}.

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.

Doubling Cube

{3}, {T}: Double the amount of each type of unspent mana you have.

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature.

Dark Ritual

Astarion's Thirst

Exile target creature. Put X +1/+1 counters on a commander creature you control, where X is the power of the creature exiled this way.

Cruel Reality

Enchant player
At the beginning of enchanted player's upkeep, that player sacrifices a creature or planeswalker. If the player can't, they lose 5 life.

Kindred Dominance

Choose a creature type. Destroy all creatures that aren't of the chosen type.

Ghirapur Orrery

Each player may play an additional land on each of their turns.
At the beginning of each player's upkeep, if that player has no cards in hand, that player draws three cards.

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Swamp

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Lord Skitter, Sewer King

Whenever another Rat you control enters, exile up to one target card from an opponent's graveyard.
At the beginning of combat on your turn, create a 1/1 black Rat creature token with "This creature can't block."

In Garruk's Wake

Destroy all creatures you don't control and all planeswalkers you don't control.

No Mercy

Whenever a creature deals damage to you, destroy it.

Mox Amber

{T}: Add one mana of any color among legendary creatures and planeswalkers you control.

Vesuva

You may have Vesuva enter tapped as a copy of any land on the battlefield.

Pyramid of the Pantheon

{2}, {T}: Add one mana of any color. Put a brick counter on Pyramid of the Pantheon.
{T}: Add three mana of any one color. Activate only if there are three or more brick counters on Pyramid of the Pantheon.

Ashcoat of the Shadow Swarm

Whenever Ashcoat of the Shadow Swarm attacks or blocks, other Rats you control get +X/+X until end of turn, where X is the number of Rats you control.
At the beginning of your end step, you may mill four cards. If you do, return up to two Rat creature cards from your graveyard to your hand. (To mill a card, put the top card of your library into your graveyard.)

Ancient Craving

Demonic Tutor

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

Candelabra of Tawnos

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.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Crawlspace

No more than two creatures can attack you each combat.

Throne of Eldraine

As Throne of Eldraine enters, choose a color.
{T}: Add four mana of the chosen color. Spend this mana only to cast monocolored spells of that color.
{3}, {T}: Draw two cards. Spend only mana of the chosen color to activate this ability.

Bubble Matrix

Prevent all damage that would be dealt to creatures.

Dredge the Mire

Each opponent chooses a creature card in their graveyard. Put those cards onto the battlefield under your control.

Make an Example

Each opponent separates the creatures they control into two piles. For each opponent, you choose one of their piles. Each opponent sacrifices the creatures in their chosen pile. (Piles can be empty.)

Beacon of Unrest

Put target artifact or creature card from a graveyard onto the battlefield under your control. Shuffle Beacon of Unrest into its owner's library.

Commander's Sphere

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

Akroma's Memorial

Creatures you control have flying, first strike, vigilance, trample, haste, and protection from black and from red.

Karumonix, the Rat King

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Other Rats you control have toxic 1.
When Karumonix enters, look at the top five cards of your library. You may reveal any number of Rat cards from among them and put the revealed cards into your hand. Put the rest on the bottom of your library in a random order.

Hall of Triumph

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

Beseech the Queen

({2/B} can be paid with any two mana or with {B}. This card's mana value is 6.)
Search your library for a card with mana value less than or equal to the number of lands you control, reveal it, put it into your hand, then shuffle.

Bad Moon

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature.

Cosmos Elixir

At the beginning of your end step, draw a card if your life total is greater than your starting life total. Otherwise, you gain 2 life.

Font of Mythos

At the beginning of each player's draw step, that player draws two additional cards.

Adaptive Automaton

As Adaptive Automaton enters, choose a creature type.
Adaptive Automaton is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Urborg, Tomb of Yawgmoth

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

Crypt of Agadeem

Crypt of Agadeem enters tapped.
{T}: Add {B}.
{2}, {T}: Add {B} for each black creature card in your graveyard.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Extraplanar Lens

Imprint — When Extraplanar Lens enters, you may exile target land you control.
Whenever a land with the same name as the exiled card is tapped for mana, its controller adds one mana of any type that land produced.

Mind's Eye

Whenever an opponent draws a card, you may pay {1}. If you do, draw a card.

Crippling Fear

Choose a creature type. Creatures that aren't of the chosen type get -3/-3 until end of turn.

Command the Dreadhorde

Choose any number of target creature and/or planeswalker cards in graveyards. Command the Dreadhorde deals damage to you equal to the total mana value of those cards. Put them onto the battlefield under your control.

Cabal Coffers

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

Fated Return

Put target creature card from a graveyard onto the battlefield under your control. It gains indestructible. If it's your turn, scry 2.

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

Caged Sun

As Caged Sun enters, choose a color.
Creatures you control of the chosen color get +1/+1.
Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Diabolic Intent

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a card, put that card into your hand, then shuffle.