Mairsil, the Pretender

When Mairsil, the Pretender enters, you may exile an artifact or creature card from your hand or graveyard and put a cage counter on it.
Mairsil, the Pretender has all activated abilities of all cards you own in exile with cage counters on them. You may activate each of those abilities only once each turn.

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

Cinderhaze Wretch

{T}: Target player discards a card. Activate only during your turn.
Put a -1/-1 counter on Cinderhaze Wretch: Untap Cinderhaze Wretch.

Displacer Kitten

Avoidance — Whenever you cast a noncreature spell, exile up to one target nonland permanent you control, then return that card to the battlefield under its owner's control.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Drowned Catacomb

Drowned Catacomb enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Cavern Harpy

Flying
When Cavern Harpy enters, return a blue or black creature you control to its owner's hand.
Pay 1 life: Return Cavern Harpy to its owner's hand.

Magus of the Bazaar

{T}: Draw two cards, then discard three cards.

Necrotic Ooze

As long as Necrotic Ooze is on the battlefield, it has all activated abilities of all creature cards in all graveyards.

Pili-Pala

Flying
{2}, {Q}: Add one mana of any color. ({Q} is the untap symbol.)

Essence Flux

Exile target creature you control, then return that card to the battlefield under its owner's control. If it's a Spirit, put a +1/+1 counter on it.

Thassa's Oracle

When Thassa's Oracle enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Blood Vassal

Horseshoe Crab

Luxury Suite

Luxury Suite enters tapped unless you have two or more opponents.
{T}: Add {B} or {R}.

Nevinyrral's Disk

Nevinyrral's Disk enters tapped.
{1}, {T}: Destroy all artifacts, creatures, and enchantments.

Tree of Perdition

Defender
{T}: Exchange target opponent's life total with Tree of Perdition's toughness.

Quicksilver Elemental

{U}: Quicksilver Elemental gains all activated abilities of target creature until end of turn. (If any of the abilities use that creature's name, use this creature's name instead.)
You may spend blue mana as though it were mana of any color to pay the activation costs of Quicksilver Elemental's abilities.

Pongify

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

Island

Boots of Speed

Equipped creature gets +1/+0 and has haste.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Stitcher's Supplier

When Stitcher's Supplier enters or dies, mill three cards. (Put the top three cards of your library into your graveyard.)

Blood Pet

Triskelion

Triskelion enters with three +1/+1 counters on it.
Remove a +1/+1 counter from Triskelion: It deals 1 damage to any target.

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Chromatic Lantern

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

Ransack the Lab

Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

Teferi's Time Twist

Exile target permanent you control. Return that card to the battlefield under its owner's control at the beginning of the next end step. If it enters as a creature, it enters with an additional +1/+1 counter on it.

Hateflayer

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{2}{R}, {Q}: Hateflayer deals damage equal to its power to any target. ({Q} is the untap symbol.)

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis to its owner's hand.

Assassin Initiate

{1}: Assassin Initiate gains your choice of flying, deathtouch, or lifelink until end of turn.

Mirror-Mad Phantasm

Flying
{1}{U}: Mirror-Mad Phantasm's owner shuffles it into their library. If that player does, they reveal cards from the top of that library until a card named Mirror-Mad Phantasm is revealed. The player puts that card onto the battlefield and all other cards revealed this way into their graveyard.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Planar Incision

Exile target artifact or creature, then return it to the battlefield under its owner's control with a +1/+1 counter on it.

Chainer, Dementia Master

All Nightmares get +1/+1.
{B}{B}{B}, Pay 3 life: Put target creature card from a graveyard onto the battlefield under your control. That creature is black and is a Nightmare in addition to its other creature types.
When Chainer, Dementia Master leaves the battlefield, exile all Nightmares.

Ripples of Undeath

At the beginning of your first main phase, mill three cards. Then you may pay {1} and 3 life. If you do, put a card from among those cards into your hand.

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

Staff of Domination

{1}: Untap Staff of Domination.
{2}, {T}: You gain 1 life.
{3}, {T}: Untap target creature.
{4}, {T}: Tap target creature.
{5}, {T}: Draw a card.

Crumbling Necropolis

Crumbling Necropolis enters tapped.
{T}: Add {U}, {B}, or {R}.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Mountain

Morphic Pool

Morphic Pool enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

Hammer of Purphoros

Creatures you control have haste.
{2}{R}, {T}, Sacrifice a land: Create a 3/3 colorless Golem enchantment artifact creature token.

Training Center

Training Center enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Otherworldly Gaze

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Dragonskull Summit

Dragonskull Summit enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Lavaspur Boots

Equipped creature gets +1/+0 and has haste and ward {1}. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)
Equip {1}

Xander's Lounge

({T}: Add {U}, {B}, or {R}.)
Xander's Lounge enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Asmodeus the Archfiend

Binding Contract — If you would draw a card, exile the top card of your library face down instead.
{B}{B}{B}: Draw seven cards.
{B}: Return all cards exiled with Asmodeus the Archfiend to their owner's hand and you lose that much life.

Marvin, Murderous Mimic

Marvin, Murderous Mimic has all activated abilities of creatures you control that don't have the same name as this creature.

Swamp

Anger

Haste
As long as Anger is in your graveyard and you control a Mountain, creatures you control have haste.

Mass Hysteria

Spikeshot Elder

{1}{R}{R}: Spikeshot Elder deals damage equal to its power to any target.

Haunted Cloak

Equipped creature has vigilance, trample, and haste.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Release to the Wind

Exile target nonland permanent. For as long as that card remains exiled, its owner may cast it without paying its mana cost.

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

Illusionist's Bracers

Whenever an ability of equipped creature is activated, if it isn't a mana ability, copy that ability. You may choose new targets for the copy.
Equip {3}

Aetherling

{U}: Exile Aetherling. Return it to the battlefield under its owner's control at the beginning of the next end step.
{U}: Aetherling can't be blocked this turn.
{1}: Aetherling gets +1/-1 until end of turn.
{1}: Aetherling gets -1/+1 until end of turn.

Gilded Lotus

Exotic Orchard

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

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Command Tower

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

Fervor

Creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Riptide Laboratory

{T}: Add {C}.
{1}{U}, {T}: Return target Wizard you control to its owner's hand.

Endling

{B}: Endling gains menace until end of turn.
{B}: Endling gains deathtouch until end of turn.
{B}: Endling gains undying until end of turn. (When this creature 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.)
{1}: Endling gets +1/-1 or -1/+1 until end of turn.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Blur

Exile target creature you control, then return that card to the battlefield under its owner's control.
Draw a card.

Battlemage's Bracers

Equipped creature has haste.
Whenever an ability of equipped creature is activated, if it isn't a mana ability, you may pay {1}. If you do, copy that ability. You may choose new targets for the copy.
Equip {2}

Cathartic Reunion

As an additional cost to cast this spell, discard two cards.
Draw three cards.

Mirage Mirror

{2}: Mirage Mirror becomes a copy of target artifact, creature, enchantment, or land until end of turn.