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.

Prismatic Vista

{T}, Pay 1 life, Sacrifice Prismatic Vista: Search your library for a basic land card, put it onto the battlefield, then shuffle.

Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Walking Ballista

Walking Ballista enters the battlefield with X +1/+1 counters on it.
{4}: Put a +1/+1 counter on Walking Ballista.
Remove a +1/+1 counter from Walking Ballista: It deals 1 damage to any target.

Undergrowth Stadium

Undergrowth Stadium enters the battlefield tapped unless you have two or more opponents.
{T}: Add {B} or {G}.

Kataki, War's Wage

All artifacts have "At the beginning of your upkeep, sacrifice this artifact unless you pay {1}."

Karmic Guide

Flying, protection from black
Echo {3}{W}{W} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Karmic Guide enters the battlefield, return target creature card from your graveyard to the battlefield.

Arbor Elf

Grand Abolisher

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

Temple Garden

({T}: Add {G} or {W}.)
As Temple Garden enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Ghave, Guru of Spores

Ghave, Guru of Spores enters the battlefield with five +1/+1 counters on it.
{1}, Remove a +1/+1 counter from a creature you control: Create a 1/1 green Saproling creature token.
{1}, Sacrifice a creature: Put a +1/+1 counter on target creature.

Bayou

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Defense Grid

Each spell costs {3} more to cast except during its controller's turn.

Tayam, Luminous Enigma

Each other creature you control enters the battlefield with an additional vigilance counter on it.
{3}, Remove three counters from among creatures you control: Mill three cards, then return a permanent card with mana value 3 or less from your graveyard to the battlefield.

Cathars' Crusade

Whenever a creature enters the battlefield under your control, put a +1/+1 counter on each creature you control.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Bloom Tender

{T}: For each color among permanents you control, add one mana of that color.

Swords to Plowshares

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

Young Wolf

Undying (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.)

Pattern of Rebirth

Enchant creature
When enchanted creature dies, that creature's controller may search their library for a creature card, put that card onto the battlefield, then shuffle.

Green Sun's Zenith

Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.

Swamp

Phyrexian Tower

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

Verdant Catacombs

{T}, Pay 1 life, Sacrifice Verdant Catacombs: Search your library for a Swamp or Forest card, put it onto the battlefield, then shuffle.

Gaea's Cradle

{T}: Add {G} for each creature you control.

Academy Rector

When Academy Rector dies, you may exile it. If you do, search your library for an enchantment card, put that card onto the battlefield, then shuffle.

Sol Ring

Forbidden Orchard

{T}: Add one mana of any color.
Whenever you tap Forbidden Orchard for mana, target opponent creates a 1/1 colorless Spirit creature token.

Overgrown Tomb

({T}: Add {B} or {G}.)
As Overgrown Tomb enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Fyndhorn Elves

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Savannah

Grim Tutor

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

Demonic Tutor

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

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Generous Patron

When Generous Patron enters the battlefield, support 2. (Put a +1/+1 counter on each of up to two other target creatures.)
Whenever you put one or more counters on a creature you don't control, draw a card.

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Linvala, Keeper of Silence

Flying
Activated abilities of creatures your opponents control can't be activated.

Mikaeus, the Unhallowed

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a Human deals damage to you, destroy it.
Other non-Human creatures you control get +1/+1 and have undying. (When a creature with undying 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.)

Wild Growth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}.

Bountiful Promenade

Bountiful Promenade enters the battlefield tapped unless you have two or more opponents.
{T}: Add {G} or {W}.

Vampiric Tutor

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

Spike Weaver

Spike Weaver enters the battlefield with three +1/+1 counters on it.
{2}, Remove a +1/+1 counter from Spike Weaver: Put a +1/+1 counter on target creature.
{1}, Remove a +1/+1 counter from Spike Weaver: Prevent all combat damage that would be dealt this turn.

Finale of Devastation

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.

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}

Command Tower

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

Twilight Mire

{T}: Add {C}.
{B/G}, {T}: Add {B}{B}, {B}{G}, or {G}{G}.

Sunpetal Grove

Sunpetal Grove enters the battlefield tapped unless you control a Forest or a Plains.
{T}: Add {G} or {W}.

Misty Rainforest

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Avacyn's Pilgrim

Eldritch Evolution

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a creature card with mana value X or less, where X is 2 plus the sacrificed creature's mana value. Put that card onto the battlefield, then shuffle. Exile Eldritch Evolution.

Corpse Knight

Whenever another creature enters the battlefield under your control, each opponent loses 1 life.

Good-Fortune Unicorn

Whenever another creature enters the battlefield under your control, put a +1/+1 counter on that creature.

Ranger-Captain of Eos

When Ranger-Captain of Eos enters the battlefield, you may search your library for a creature card with mana value 1 or less, reveal it, put it into your hand, then shuffle.
Sacrifice Ranger-Captain of Eos: Your opponents can't cast noncreature spells this turn.

Bloodstained Mire

{T}, Pay 1 life, Sacrifice Bloodstained Mire: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Bitter Ordeal

Search target player's library for a card and exile it. Then that player shuffles.
Gravestorm (When you cast this spell, copy it for each permanent put into a graveyard this turn. You may choose new targets for the copies.)

Butcher Ghoul

Grave Pact

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

Anafenza, the Foremost

Whenever Anafenza, the Foremost attacks, put a +1/+1 counter on another target tapped creature you control.
If a nontoken creature an opponent owns would die or a creature card not on the battlefield would be put into an opponent's graveyard, exile that card instead.

Chord of Calling

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Scavenging Ooze

{G}: Exile target card from a graveyard. If it was a creature card, put a +1/+1 counter on Scavenging Ooze and you gain 1 life.

Natural Order

As an additional cost to cast this spell, sacrifice a green creature.
Search your library for a green creature card, put it onto the battlefield, then shuffle.

Plains

Aura Shards

Whenever a creature enters the battlefield under your control, you may destroy target artifact or enchantment.

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

Earthcraft

Tap an untapped creature you control: Untap target basic land.

Wooded Foothills

{T}, Pay 1 life, Sacrifice Wooded Foothills: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Abrupt Decay

This spell can't be countered.
Destroy target nonland permanent with mana value 3 or less.

Arid Mesa

{T}, Pay 1 life, Sacrifice Arid Mesa: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Urborg, Tomb of Yawgmoth

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

Saffi Eriksdotter

Sacrifice Saffi Eriksdotter: When target creature is put into your graveyard this turn, return that card to the battlefield.

Toski, Bearer of Secrets

This spell can't be countered.
Indestructible
Toski, Bearer of Secrets attacks each combat if able.
Whenever a creature you control deals combat damage to a player, draw a card.

Necropotence

Skip your draw step.
Whenever you discard a card, exile that card from your graveyard.
Pay 1 life: Exile the top card of your library face down. Put that card into your hand at the beginning of your next end step.

Enlightened Tutor

Search your library for an artifact or enchantment card, reveal it, then shuffle and put that card on top.

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.

Collector Ouphe

Activated abilities of artifacts can't be activated.

Geralf's Messenger

Geralf's Messenger enters the battlefield tapped.
When Geralf's Messenger enters the battlefield, target opponent loses 2 life.
Undying (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.)

Utopia Sprawl

Enchant Forest
As Utopia Sprawl enters the battlefield, choose a color.
Whenever enchanted Forest is tapped for mana, its controller adds an additional one mana of the chosen color.

Polluted Delta

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Dryad Arbor

(Dryad Arbor isn't a spell, it's affected by summoning sickness, and it has "{T}: Add {G}.")

Sylvan Library

At the beginning of your draw step, you may draw two additional cards. If you do, choose two cards in your hand drawn this turn. For each of those cards, pay 4 life or put the card on top of your library.

Protean Hulk

When Protean Hulk dies, search your library for any number of creature cards with total mana value 6 or less, put them onto the battlefield, then shuffle.

Cryptic Trilobite

Cryptic Trilobite enters the battlefield with X +1/+1 counters on it.
Remove a +1/+1 counter from Cryptic Trilobite: Add {C}{C}. Spend this mana only to activate abilities.
{1}, {T}: Put a +1/+1 counter on Cryptic Trilobite.

City of Solitude

Players can cast spells and activate abilities only during their own turns.

Champion of Lambholt

Creatures with power less than Champion of Lambholt's power can't block creatures you control.
Whenever another creature enters the battlefield under your control, put a +1/+1 counter on Champion of Lambholt.

Devoted Druid

{T}: Add {G}.
Put a -1/-1 counter on Devoted Druid: Untap Devoted Druid.

Flooded Strand

{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Sanctum Weaver

{T}: Add X mana of any one color, where X is the number of enchantments you control.

Eladamri's Call

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

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Survival of the Fittest

{G}, Discard a creature card: Search your library for a creature card, reveal that card, put it into your hand, then shuffle.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Squirrel Nest

Enchant land
Enchanted land has "{T}: Create a 1/1 green Squirrel creature token."

Ashnod's Altar

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}.

Nurturing Peatland

{T}, Pay 1 life: Add {B} or {G}.
{1}, {T}, Sacrifice Nurturing Peatland: Draw a card.

Forest

Birds of Paradise

Elves of Deep Shadow

{T}: Add {B}. Elves of Deep Shadow deals 1 damage to you.

Marsh Flats

{T}, Pay 1 life, Sacrifice Marsh Flats: Search your library for a Plains or Swamp card, put it onto the battlefield, then shuffle.

Godless Shrine

({T}: Add {W} or {B}.)
As Godless Shrine enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Woodland Cemetery

Woodland Cemetery enters the battlefield tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Eternal Witness

When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.

Windswept Heath

{T}, Pay 1 life, Sacrifice Windswept Heath: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.