Definitely

Fractured Identity

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

Expensive

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: Aetherflux Reservoir deals 50 damage to any target.

Maybe

Smoke

Players can't untap more than one creature during their untap steps.

Taniwha

Trample
Phasing (This phases in or out before you untap during each of your untap steps. While it's phased out, it's treated as though it doesn't exist.)
At the beginning of your upkeep, all lands you control phase out. (They phase in before you untap during your next untap step.)

Chaos Wand

{4}, {T}: Target opponent exiles cards from the top of their library until they exile an instant or sorcery card. You may cast that card without paying its mana cost. Then put the exiled cards that weren't cast this way on the bottom of that library in a random order.

Fellwar Stone

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

Highland Lake

Highland Lake enters tapped.
{T}: Add {U} or {R}.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Owned

Plains

Kazuul, Tyrant of the Cliffs

Whenever a creature an opponent controls attacks, if you're the defending player, create a 3/3 red Ogre creature token unless that creature's controller pays {3}.

Idyllic Tutor

Search your library for an enchantment card, reveal it, put it into your hand, then shuffle.

Felidar Sovereign

Vigilance (Attacking doesn't cause this creature to tap.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
At the beginning of your upkeep, if you have 40 or more life, you win the game.

Humble Defector

{T}: Draw two cards. Target opponent gains control of Humble Defector. Activate only during your turn.

Thought Lash

Cumulative upkeep—Exile the top card of your library. (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.)
When a player doesn't pay Thought Lash's cumulative upkeep, that player exiles all cards from their library.
Exile the top card of your library: Prevent the next 1 damage that would be dealt to you this turn.

Daring Thief

Inspired — Whenever Daring Thief becomes untapped, you may exchange control of target nonland permanent you control and target permanent an opponent controls that shares a card type with it.

Brand

Gain control of all permanents you own. (This effect lasts indefinitely.)
Cycling {2} ({2}, Discard this card: Draw a card.)

Swiftwater Cliffs

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

Treasure Nabber

Whenever an opponent taps an artifact for mana, gain control of that artifact until the end of your next turn.

Clever Impersonator

You may have Clever Impersonator enter as a copy of any nonland permanent on the battlefield.

Form of the Dinosaur

When Form of the Dinosaur enters, your life total becomes 15.
At the beginning of your upkeep, Form of the Dinosaur deals 15 damage to target creature an opponent controls and that creature deals damage equal to its power to you.

Order of Succession

Choose left or right. Starting with you and proceeding in the chosen direction, each player chooses a creature controlled by the next player in that direction. Each player gains control of the creature they chose.

Exotic Orchard

Capricious Efreet

At the beginning of your upkeep, choose target nonland permanent you control and up to two target nonland permanents you don't control. Destroy one of them at random.

Grip of Chaos

Whenever a spell or ability is put onto the stack, if it has a single target, reselect its target at random. (Select from among all legal targets.)

Rapid Hybridization

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

Switcheroo

Exchange control of two target creatures.

Island

Omen Machine

Players can't draw cards.
At the beginning of each player's draw step, that player exiles the top card of their library. If it's a land card, the player puts it onto the battlefield. Otherwise, the player casts it without paying its mana cost if able.

Psychosis Crawler

Psychosis Crawler's power and toughness are each equal to the number of cards in your hand.
Whenever you draw a card, each opponent loses 1 life.

Political Trickery

Exchange control of target land you control and target land an opponent controls. (This effect lasts indefinitely.)

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.

Chromeshell Crab

Morph {4}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Chromeshell Crab is turned face up, you may exchange control of target creature you control and target creature an opponent controls.

Reliquary Tower

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

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.

Jinxed Ring

Whenever a nontoken permanent is put into your graveyard from the battlefield, Jinxed Ring deals 1 damage to you.
Sacrifice a creature: Target opponent gains control of Jinxed Ring. (This effect lasts indefinitely.)

Ruhan of the Fomori

At the beginning of combat on your turn, choose an opponent at random. Ruhan of the Fomori attacks that player this combat if able.

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.

Confusion in the Ranks

Whenever an artifact, creature, or enchantment enters, its controller chooses target permanent another player controls that shares a card type with it. Exchange control of those permanents.

Loxodon Peacekeeper

At the beginning of your upkeep, the player with the lowest life total gains control of Loxodon Peacekeeper. If two or more players are tied for lowest life total, you choose one of them, and that player gains control of Loxodon Peacekeeper.

Goldnight Castigator

Flying, haste
If a source would deal damage to you, it deals double that damage to you instead.
If a source would deal damage to Goldnight Castigator, it deals double that damage to Goldnight Castigator instead.

Grafdigger's Cage

Creature cards in graveyards and libraries can't enter the battlefield.
Players can't cast spells from graveyards or libraries.

Blatant Thievery

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

Starfield of Nyx

At the beginning of your upkeep, you may return target enchantment card from your graveyard to the battlefield.
As long as you control five or more enchantments, each other non-Aura enchantment you control is a creature in addition to its other types and has base power and base toughness each equal to its mana value.

Gwafa Hazid, Profiteer

{W}{U}, {T}: Put a bribery counter on target creature you don't control. Its controller draws a card.
Creatures with bribery counters on them can't attack or block.

Volatile Rig

Trample
Volatile Rig attacks each combat if able.
Whenever Volatile Rig is dealt damage, flip a coin. If you lose the flip, sacrifice Volatile Rig.
When Volatile Rig dies, flip a coin. If you lose the flip, it deals 4 damage to each creature and each player.

Planar Chaos

At the beginning of your upkeep, flip a coin. If you lose the flip, sacrifice Planar Chaos.
Whenever a player casts a spell, that player flips a coin. If they lose the flip, counter that spell.

Puca's Mischief

At the beginning of your upkeep, you may exchange control of target nonland permanent you control and target nonland permanent an opponent controls with equal or lesser mana value.

Hunted Dragon

Flying, haste
When Hunted Dragon enters, target opponent creates three 2/2 white Knight creature tokens with first strike.

Perplexing Chimera

Whenever an opponent casts a spell, you may exchange control of Perplexing Chimera and that spell. If you do, you may choose new targets for the spell. (If the spell becomes a permanent, you control that permanent.)

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Transcendence

You don't lose the game for having 0 or less life.
When you have 20 or more life, you lose the game.
Whenever you lose life, you gain 2 life for each 1 life you lost. (Damage dealt to you causes you to lose life.)

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Tranquil Cove

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

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Statecraft

Prevent all combat damage that would be dealt to and dealt by creatures you control.

Shifting Borders

Exchange control of two target lands.
Splice onto Arcane {3}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Risky Move

At the beginning of each player's upkeep, that player gains control of Risky Move.
When you gain control of Risky Move from another player, choose a creature you control and an opponent. Flip a coin. If you lose the flip, that opponent gains control of that creature.

Harmless Offering

Target opponent gains control of target permanent you control.

Scrambleverse

For each nonland permanent, choose a player at random. Then each player gains control of each permanent for which they were chosen. Untap those permanents.

Shared

Path of Ancestry

Path of Ancestry enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Dimensional Breach

Exile all permanents. For as long as any of those cards remain exiled, at the beginning of each player's upkeep, that player returns one of the exiled cards they own to the battlefield.

Trickbind

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Counter target activated or triggered ability. If a permanent's ability is countered this way, activated abilities of that permanent can't be activated this turn. (Mana abilities can't be targeted.)

Cultural Exchange

Choose any number of creatures target player controls. Choose the same number of creatures another target player controls. Those players exchange control of those creatures. (This effect lasts indefinitely.)

Pendant of Prosperity

Pendant of Prosperity enters under the control of an opponent of your choice.
{2}, {T}: Draw a card, then you may put a land card from your hand onto the battlefield. Pendant of Prosperity's owner draws a card, then that player may put a land card from their hand onto the battlefield.

Rust Elemental

Flying
At the beginning of your upkeep, sacrifice an artifact other than Rust Elemental. If you can't, tap Rust Elemental and you lose 4 life.

Cinder Giant

At the beginning of your upkeep, Cinder Giant deals 2 damage to each other creature you control.

Dovin's Veto

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

Orzhov Advokist

At the beginning of your upkeep, each player may put two +1/+1 counters on a creature they control. If a player does, creatures that player controls can't attack you or planeswalkers you control until your next turn.

Polymorphist's Jest

Until end of turn, each creature target player controls loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Akroan Horse

Defender
When Akroan Horse enters, an opponent gains control of it.
At the beginning of your upkeep, each opponent creates a 1/1 white Soldier creature token.

Wild Evocation

At the beginning of each player's upkeep, that player reveals a card at random from their hand. If it's a land card, the player puts it onto the battlefield. Otherwise, the player casts it without paying its mana cost if able.

Approach of the Second Sun

If this spell was cast from your hand and you've cast another spell named Approach of the Second Sun this game, you win the game. Otherwise, put Approach of the Second Sun into its owner's library seventh from the top and you gain 7 life.

Angel's Grace

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
You can't lose the game this turn and your opponents can't win the game this turn. Until end of turn, damage that would reduce your life total to less than 1 reduces it to 1 instead.

Shared Fate

If a player would draw a card, that player exiles the top card of one of their opponents' libraries face down instead.
Each player may look at cards they exiled with Shared Fate, and they may play lands and cast spells from among those cards.

Spawnbroker

When Spawnbroker enters, you may exchange control of target creature you control and target creature with power less than or equal to that creature's power an opponent controls.

Wild Research

{1}{W}: Search your library for an enchantment card and reveal that card. Put it into your hand, then discard a card at random. Then shuffle.
{1}{U}: Search your library for an instant card and reveal that card. Put it into your hand, then discard a card at random. Then shuffle.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Djinn of Infinite Deceits

Flying
{T}: Exchange control of two target nonlegendary creatures. You can't activate this ability during combat.

Thieves' Auction

Exile all nontoken permanents. Starting with you, each player chooses one of the exiled cards and puts it onto the battlefield tapped under their control. Repeat this process until all cards exiled this way have been chosen.

Benevolent Offering

Choose an opponent. You and that player each create three 1/1 white Spirit creature tokens with flying.
Choose an opponent. You gain 2 life for each creature you control and that player gains 2 life for each creature they control.

Witch Hunt

Players can't gain life.
At the beginning of your upkeep, Witch Hunt deals 4 damage to you.
At the beginning of your end step, target opponent chosen at random gains control of Witch Hunt.

Fortunate Few

Choose a nonland permanent you don't control, then each other player chooses a nonland permanent they don't control that hasn't been chosen this way. Destroy all other nonland permanents.

Oblation

The owner of target nonland permanent shuffles it into their library, then draws two cards.

Sudden Substitution

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Exchange control of target noncreature spell and target creature. Then the spell's controller may choose new targets for it.

Insurrection

Untap all creatures and gain control of them until end of turn. They gain haste until end of turn.

Psychic Battle

Whenever a player chooses one or more targets, each player reveals the top card of their library. The player who reveals the card with the highest mana value may change the target or targets. If two or more cards are tied for highest, the target or targets remain unchanged. Changing targets this way doesn't trigger abilities of permanents named Psychic Battle.

Grid Monitor

Boompile

{T}: Flip a coin. If you win the flip, destroy all nonland permanents.

Mountain

Swords to Plowshares

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

Legerdemain

Exchange control of target artifact or creature and another target permanent that shares one of those types with it. (This effect lasts indefinitely.)

Role Reversal

Exchange control of two target permanents that share a permanent type.

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Bazaar Trader

{T}: Target player gains control of target artifact, creature, or land you control.

Toothy, Imaginary Friend

Partner with Pir, Imaginative Rascal (When this creature enters, target player may put Pir into their hand from their library, then shuffle.)
Whenever you draw a card, put a +1/+1 counter on Toothy, Imaginary Friend.
When Toothy leaves the battlefield, draw a card for each +1/+1 counter on it.

Experimental Frenzy

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library.
You can't play lands or cast spells from your hand.
{3}{R}: Destroy Experimental Frenzy.

Plea for Guidance

Search your library for up to two enchantment cards, reveal them, put them into your hand, then shuffle.

Word of Seizing

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Untap target permanent and gain control of it until end of turn. It gains haste until end of turn.

Chasm Skulker

Whenever you draw a card, put a +1/+1 counter on Chasm Skulker.
When Chasm Skulker dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on Chasm Skulker. (They can't be blocked as long as defending player controls an Island.)

Leveler

When Leveler enters, exile all cards from your library.

Puppet's Verdict

Flip a coin. If you win the flip, destroy all creatures with power 2 or less. If you lose the flip, destroy all creatures with power 3 or greater.