Cackling Counterpart

Create a token that's a copy of target creature you control.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mind Flayer

Dominate Monster — When this creature enters, gain control of target creature for as long as you control this creature.

Tranquil Cove

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {W} or {U}.

Blue Sun's Twilight

Gain control of target creature with mana value X or less. If X is 5 or more, create a token that's a copy of that creature.

Evil Twin

You may have this creature enter as a copy of any creature on the battlefield, except it has "{U}{B}, {T}: Destroy target creature with the same name as this creature."

Kotose, the Silent Spider

When Kotose enters, exile target card other than a basic land card from an opponent's graveyard. Search that player's graveyard, hand, and library for any number of cards with the same name as that card and exile them. Then that player shuffles. For as long as you control Kotose, you may play one of the exiled cards, and you may spend mana as though it were mana of any color to cast it.

Clone

You may have this creature enter as a copy of any creature on the battlefield.

Contaminated Aquifer

({T}: Add {U} or {B}.)
This land enters tapped.

Agent of Treachery

When this creature enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Mass Manipulation

Gain control of X target creatures and/or planeswalkers.

Coral Atoll

This land enters tapped.
When this land enters, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.

Skycloud Expanse

Dragonlord Silumgar

Flying, deathtouch
When Dragonlord Silumgar enters, gain control of target creature or planeswalker for as long as you control Dragonlord Silumgar.

Dismal Backwater

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {B}.

Scoured Barrens

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {W} or {B}.

Island

Aethersnatch

Gain control of target spell. You may choose new targets for it. (If that spell becomes a permanent, it enters under your control.)

Blatant Thievery

For each opponent, gain control of target permanent that player controls.

Orzhov Basilica

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {W}{B}.

Thran Dynamo

Fractured Identity

Exile target nonland permanent. Each player other than its controller creates a token that's a copy of it.

Nihiloor

When Nihiloor enters, for each opponent, tap up to one untapped creature you control. When you do, gain control of target creature that player controls with power less than or equal to the tapped creature's power for as long as you control Nihiloor.
Whenever you attack with a creature an opponent owns, you gain 2 life and that player loses 2 life.

Callidus Assassin

Flash
Polymorphine — You may have this creature enter tapped as a copy of any creature on the battlefield, except it has "When this creature enters, destroy up to one other target creature with the same name as this creature."

Roil Elemental

Flying
Landfall — Whenever a land you control enters, you may gain control of target creature for as long as you control this creature.

Rogue Class

(Gain the next level as a sorcery to add its ability.)
Whenever a creature you control deals combat damage to a player, exile the top card of that player's library face down. You may look at it for as long as it remains exiled.
{1}{U}{B}: Level 2
Creatures you control have menace.
{2}{U}{B}: Level 3
You may play cards exiled with this Class, and you may spend mana as though it were mana of any color to cast those spells.

Aura Thief

Flying
When this creature dies, you gain control of all enchantments. (You don't get to move Auras.)

Cytoplast Manipulator

Graft 2 (This creature enters with two +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{U}, {T}: Gain control of target creature with a +1/+1 counter on it for as long as this creature remains on the battlefield.

Grafted Identity

As an additional cost to cast this spell, sacrifice a creature.
Enchant creature
You control enchanted creature.
Enchanted creature gets +1/+1.

Dimir Guildgate

This land enters tapped.
{T}: Add {U} or {B}.

Sejiri Refuge

Keiga, the Tide Star

Flying
When Keiga dies, gain control of target creature.

Gilded Lotus

Memnarch

{1}{U}{U}: Target permanent becomes an artifact in addition to its other types. (This effect lasts indefinitely.)
{3}{U}: Gain control of target artifact. (This effect lasts indefinitely.)

Shield Broker

When this creature enters, put a shield counter on target noncommander creature you don't control. You gain control of that creature for as long as it has a shield counter on it. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

Clone Legion

For each creature target player controls, create a token that's a copy of that creature.

Aura Graft

Gain control of target Aura that's attached to a permanent. Attach it to another permanent it can enchant.

Sisay's Ring

Entrancing Melody

Gain control of target creature with mana value X.

Swamp

Jwar Isle Refuge

Herald of Leshrac

Flying
Cumulative upkeep—Gain control of a land you don't control. (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.)
This creature gets +1/+1 for each land you control but don't own.
When this creature leaves the battlefield, each player gains control of each land they own that you control.

Dimir Aqueduct

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Siren of the Fanged Coast

Flying
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When this creature enters, if tribute wasn't paid, gain control of target creature.

Azorius Chancery

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Clever Impersonator

You may have this creature enter as a copy of any nonland permanent on the battlefield.

Elminster's Simulacrum

For each opponent, you create a token that's a copy of up to one target creature that player controls.