Knowledge Exploitation

Prowl {3}{U} (You may cast this for its prowl cost if you dealt combat damage to a player this turn with a Rogue.)
Search target opponent's library for an instant or sorcery card. You may cast that card without paying its mana cost. Then that player shuffles.

Miscast

Counter target instant or sorcery spell unless its controller pays {3}.

Sky Diamond

Memory Plunder

You may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost.

Eel Umbra

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Mission Briefing

Surveil 2, then choose an instant or sorcery card in your graveyard. You may cast it this turn. If that spell would be put into your graveyard, exile it instead. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Toxic Deluge

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

Tidal Barracuda

Any player may cast spells as though they had flash.
Your opponents can't cast spells during your turn.

Torrential Gearhulk

Flash
When Torrential Gearhulk enters, you may cast target instant card from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Impulse

Look at the top four cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Frantic Search

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

Prismatic Lens

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

Stinging Lionfish

Whenever you cast your first spell during each opponent's turn, you may tap or untap target nonland permanent.

Swamp

Blessing of Leeches

Flash
Enchant creature
At the beginning of your upkeep, you lose 1 life.
{0}: Regenerate enchanted creature.

Crafty Cutpurse

Flash
When Crafty Cutpurse enters, each token that would be created under an opponent's control this turn is created under your control instead.

Darkwater Catacombs

Fellwar Stone

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

Unwind

Counter target noncreature spell. Untap up to three lands.

Island

Vedalken Orrery

You may cast spells as though they had flash.

Arcane Signet

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

Tainted Isle

{T}: Add {C}.
{T}: Add {U} or {B}. Activate only if you control a Swamp.

Sunken Ruins

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

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

Drowned Catacomb

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

Isochron Scepter

Imprint — When Isochron Scepter enters, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Slitherwisp

Flash
Whenever you cast another spell that has flash, you draw a card and each opponent loses 1 life.

Jin-Gitaxias, Core Augur

Flash
At the beginning of your end step, draw seven cards.
Each opponent's maximum hand size is reduced by seven.

Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Sol Ring

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Sunken Hollow

({T}: Add {U} or {B}.)
Sunken Hollow enters tapped unless you control two or more basic lands.

Go for the Throat

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Nymris, Oona's Trickster

Flash
Flying
Whenever you cast your first spell during each opponent's turn, look at the top two cards of your library. Put one of those cards into your hand and the other into your graveyard.

Morphic Pool

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

Murmuring Mystic

Whenever you cast an instant or sorcery spell, create a 1/1 blue Bird Illusion creature token with flying.

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}.

Fierce Guardianship

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

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

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.

Murkwater Pathway

Clearwater Pathway

Clearwater Pathway // Murkwater Pathway

Leyline of Anticipation

If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.

Unwinding Clock

Untap all artifacts you control during each other player's untap step.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. Talisman of Dominance deals 1 damage to you.

Voidmage Husher

Flash (You may cast this spell any time you could cast an instant.)
When Voidmage Husher enters, counter target activated ability. (Mana abilities can't be targeted.)
Whenever you cast a spell, you may return Voidmage Husher to its owner's hand.

Mystic Sanctuary

({T}: Add {U}.)
Mystic Sanctuary enters tapped unless you control three or more other Islands.
When Mystic Sanctuary enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Dramatic Reversal

Untap all nonland permanents you control.

Spire of Industry

{T}: Add {C}.
{T}, Pay 1 life: Add one mana of any color. Activate only if you control an artifact.

Pongify

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

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. Underground River deals 1 damage to you.

Faerie Tauntings

Whenever you cast a spell during an opponent's turn, you may have each opponent lose 1 life.

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.

Counterspell

Prismatic Vista

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

Drown in the Loch

Choose one —
• Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard.
• Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.

Command Tower

Cunning Nightbonder

Flash
Spells with flash you cast cost {1} less to cast and can't be countered.

Cast Down

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

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}.

Thought Vessel

Portal Mage

Flash
When Portal Mage enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)

Dimir Signet

Exotic Orchard

Minion's Return

Flash
Enchant creature
When enchanted creature dies, return that card to the battlefield under your control.

Malakir Mire

Malakir Mire enters tapped.
{T}: Add {B}.

Malakir Rebirth

Choose target creature. You lose 2 life. Until end of turn, that creature gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Malakir Rebirth // Malakir Mire

Niblis of Frost

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast an instant or sorcery spell, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Mystical Tutor

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

Rewind

Counter target spell. Untap up to four lands.

Stunt Double

Flash
You may have Stunt Double enter as a copy of any creature on the battlefield.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Notion Thief

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead that player skips that draw and you draw a card.

Loyal Drake

Flying
Lieutenant — At the beginning of combat on your turn, if you control your commander, draw a card.

Hullbreacher

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Ancient Tomb

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

Watery Grave

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

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.