Opposition Agent

Flash
You control your opponents while they're searching their libraries.
While an opponent is searching their library, they exile each card they find. You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them.

Cunning Rhetoric

Whenever an opponent attacks you and/or one or more planeswalkers you control, exile the top card of that player's library. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast it.

Mnemonic Betrayal

Exile all opponents' graveyards. You may cast spells from among those cards this turn, and mana of any type can be spent to cast them. At the beginning of the next end step, if any of those cards remain exiled, return them to their owners' graveyards.
Exile Mnemonic Betrayal.

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Cavern of Souls

As Cavern of Souls enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Chrome Mox

Imprint — When Chrome Mox enters, you may exile a nonartifact, nonland card from your hand.
{T}: Add one mana of any of the exiled card's colors.

Knowledge Pool

Imprint — When Knowledge Pool enters, each player exiles the top three cards of their library.
Whenever a player casts a spell from their hand, that player exiles it. If the player does, they may cast a spell from among other cards exiled with Knowledge Pool without paying its mana cost.

Unsummon

Return target creature to its owner's hand.

Pili-Pala

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

Zur's Weirding

Players play with their hands revealed.
If a player would draw a card, they reveal it instead. Then any other player may pay 2 life. If a player does, put that card into its owner's graveyard. Otherwise, that player draws a card.

Lightning Greaves

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

Keeper of the Accord

At the beginning of each opponent's end step, if that player controls more creatures than you, create a 1/1 white Soldier creature token.
At the beginning of each opponent's end step, if that player controls more lands than you, you may search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.

Cabal Coffers

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

Foil

You may discard an Island card and another card rather than pay this spell's mana cost.
Counter target spell.

Deafening Silence

Each player can't cast more than one noncreature spell each turn.

Silence

Your opponents can't cast spells this turn.

Counterspell

Seer's Vision

Your opponents play with their hands revealed.
Sacrifice Seer's Vision: Look at target player's hand and choose a card from it. That player discards that card. Activate only as a sorcery.

Font of Mythos

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

Jeweled Lotus

{T}, Sacrifice Jeweled Lotus: Add three mana of any one color. Spend this mana only to cast your commander.

Island

Swamp

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Gilded Lotus

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Howling Mine

At the beginning of each player's draw step, if Howling Mine is untapped, that player draws an additional card.

Folio of Fancies

Players have no maximum hand size.
{X}{X}, {T}: Each player draws X cards.
{2}{U}, {T}: Each opponent mills cards equal to the number of cards in their hand.

Demonic Tutor

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

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Sen Triplets

At the beginning of your upkeep, choose target opponent. This turn, that player can't cast spells or activate abilities and plays with their hand revealed. You may play lands and cast spells from that player's hand this turn.

Dauthi Voidwalker

Shadow (This creature can block or be blocked by only creatures with shadow.)
If a card would be put into an opponent's graveyard from anywhere, instead exile it with a void counter on it.
{T}, Sacrifice Dauthi Voidwalker: Choose an exiled card an opponent owns with a void counter on it. You may play it this turn without paying its mana cost.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Plains

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Urza's Saga gains "{T}: Add {C}."
II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Head Games

Target opponent puts the cards from their hand on top of their library. Search that player's library for that many cards. The player puts those cards into their hand, then shuffles.

Padeem, Consul of Innovation

Artifacts you control have hexproof. (They can't be the targets of spells or abilities your opponents control.)
At the beginning of your upkeep, if you control the artifact with the highest mana value or tied for the highest mana value, draw a card.

Snow-Covered Island

Ghostly Prison

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Grand Abolisher

During your turn, your opponents can't cast spells or activate abilities of artifacts, creatures, or enchantments.

Mystic Remora

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Arcane Signet

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

Grand Arbiter Augustin IV

White spells you cast cost {1} less to cast.
Blue spells you cast cost {1} less to cast.
Spells your opponents cast cost {1} more to cast.

Ethersworn Canonist

Each player who has cast a nonartifact spell this turn can't cast additional nonartifact spells.

Celestial Dawn

Lands you control are Plains.
Nonland permanents you control are white. The same is true for spells you control and nonland cards you own that aren't on the battlefield.
You may spend white mana as though it were mana of any color. You may spend other mana only as though it were colorless mana.

Force of Will

You may pay 1 life and exile a blue card from your hand rather than pay this spell's mana cost.
Counter target spell.

Snow-Covered Swamp

Urborg, Tomb of Yawgmoth

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

Chromatic Lantern

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

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Render Silent

Counter target spell. Its controller can't cast spells this turn.

Dark Ritual

Narset's Reversal

Copy target instant or sorcery spell, then return it to its owner's hand. You may choose new targets for the copy.

Windfall

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

Flood of Tears

Return all nonland permanents to their owners' hands. If you return four or more nontoken permanents you control this way, you may put a permanent card from your hand onto the battlefield.

Grand Architect

Other blue creatures you control get +1/+1.
{U}: Target artifact creature becomes blue until end of turn.
Tap an untapped blue creature you control: Add {C}{C}. Spend this mana only to cast artifact spells or activate abilities of artifacts.

Damn

Destroy target creature. A creature destroyed this way can't be regenerated.
Overload {2}{W}{W} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

Snow-Covered Plains

Drannith Magistrate

Your opponents can't cast spells from anywhere other than their hands.

Sol Ring

Praetor's Grasp

Search target opponent's library for a card and exile it face down. Then that player shuffles. You may play that card for as long as it remains exiled.

Thoughtseize

Target player reveals their hand. You choose a nonland card from it. That player discards that card. You lose 2 life.

Chromatic Orrery

You may spend mana as though it were mana of any color.
{T}: Add {C}{C}{C}{C}{C}.
{5}, {T}: Draw a card for each color among permanents you control.

Anguished Unmaking

Exile target nonland permanent. You lose 3 life.

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Sphinx of the Second Sun

Flying
At the beginning of each of your postcombat main phases, there is an additional beginning phase after this phase. (The beginning phase includes the untap, upkeep, and draw steps.)

Watery Grave

({T}: Add {U} or {B}.)
As Watery Grave enters, you may pay 2 life. If you don't, it enters tapped.

Telepathy

Your opponents play with their hands revealed.

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

Explore the Vastlands

Each player looks at the top five cards of their library and may reveal a land card and/or an instant or sorcery card from among them. Each player puts the cards they revealed this way into their hand and the rest on the bottom of their library in a random order. Each player gains 3 life.

Wandering Archaic

Whenever an opponent casts an instant or sorcery spell, they may pay {2}. If they don't, you may copy that spell. You may choose new targets for the copy.

Wandering Archaic // Explore the Vastlands

Paradox Haze

Enchant player
At the beginning of enchanted player's first upkeep each turn, that player gets an additional upkeep step after this step.

Ward of Bones

Each opponent who controls more creatures than you can't cast creature spells. The same is true for artifacts and enchantments.
Each opponent who controls more lands than you can't play lands.

Snapback

You may exile a blue card from your hand rather than pay this spell's mana cost.
Return target creature to its owner's hand.

Mana Crypt

At the beginning of your upkeep, flip a coin. If you lose the flip, Mana Crypt deals 3 damage to you.
{T}: Add {C}{C}.