Tomb of Horrors Adventurer

When Tomb of Horrors Adventurer enters the battlefield, you take the initiative.
Whenever you cast your second spell each turn, copy it. If you've completed a dungeon, copy that spell twice instead. You may choose new targets for the copies. (A copy of a permanent spell becomes a token.)

Emrakul, the Promised End

This spell costs {1} less to cast for each card type among cards in your graveyard.
When you cast this spell, you gain control of target opponent during that player's next turn. After that turn, that player takes an extra turn.
Flying, trample, protection from instants

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

Conjurer's Bauble

{T}, Sacrifice Conjurer's Bauble: Put up to one target card from your graveyard on the bottom of your library. Draw a card.

Anarchy

Spontaneous Mutation

Flash
Enchant creature
Enchanted creature gets -X/-0, where X is the number of cards in your graveyard.

Svyelunite Temple

Svyelunite Temple enters the battlefield tapped.
{T}: Add {U}.
{T}, Sacrifice Svyelunite Temple: Add {U}{U}.

Mountain

Haggle

You may discard a card. If you do, draw a card. (Then exile this card. You may cast the creature later from exile.)

Merchant of the Vale

Merchant of the Vale // Haggle

Ulamog, the Infinite Gyre

When you cast this spell, destroy target permanent.
Indestructible
Annihilator 4 (Whenever this creature attacks, defending player sacrifices four permanents.)
When Ulamog, the Infinite Gyre is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.

Arcane Bombardment

Whenever you cast your first instant or sorcery spell each turn, exile an instant or sorcery card at random from your graveyard. Then copy each card exiled with Arcane Bombardment. You may cast any number of the copies without paying their mana costs.

Jaya Ballard

+1: Add {R}{R}{R}. Spend this mana only to cast instant or sorcery spells.
+1: Discard up to three cards, then draw that many cards.
−8: You get an emblem with "You may cast instant and sorcery spells from your graveyard. If a spell cast this way would be put into your graveyard, exile it instead."

Clout of the Dominus

Enchant creature
As long as enchanted creature is blue, it gets +1/+1 and has shroud. (It can't be the target of spells or abilities.)
As long as enchanted creature is red, it gets +1/+1 and has haste.

Maximize Velocity

Target creature gets +1/+1 and gains haste until end of turn.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Ghitu Amplifier

Kicker {2}{U} (You may pay an additional {2}{U} as you cast this spell.)
When Ghitu Amplifier enters the battlefield, if it was kicked, return target creature an opponent controls to its owner's hand.
Whenever you cast an instant or sorcery spell, Ghitu Amplifier gets +2/+0 until end of turn.

Command Tower

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

Enchantment Alteration

Attach target Aura attached to a creature or land to another permanent of that type.

Aven Reedstalker

Djinn of the Fountain

Flying
Whenever you cast an instant or sorcery spell, choose one —
• Djinn of the Fountain gets +1/+1 until end of turn.
• Exile Djinn of the Fountain. Return it to the battlefield under its owner's control at the beginning of the next end step.
• Scry 1.

Crab Umbra

Enchant creature
{2}{U}: Untap enchanted creature.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Alexi's Cloak

Flash
Enchant creature
Enchanted creature has shroud. (It can't be the target of spells or abilities.)

Phyrexian Metamorph

({U/P} can be paid with either {U} or 2 life.)
You may have Phyrexian Metamorph enter the battlefield as a copy of any artifact or creature on the battlefield, except it's an artifact in addition to its other types.

Countervailing Winds

Counter target spell unless its controller pays {1} for each card in your graveyard.
Cycling {2} ({2}, Discard this card: Draw a card.)

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

The Royal Scions

+1: Draw a card, then discard a card.
+1: Target creature gets +2/+0 and gains first strike and trample until end of turn.
−8: Draw four cards. When you do, The Royal Scions deals damage to any target equal to the number of cards in your hand.

Sky Diamond

Sky Diamond enters the battlefield tapped.
{T}: Add {U}.

Sinister Sabotage

Counter target spell.
Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Run Away Together

Choose two target creatures controlled by different players. Return those creatures to their owners' hands.

Mind Stone

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

Neurok Stealthsuit

Equipped creature has shroud. (It can't be the target of spells or abilities.)
{U}{U}: Attach Neurok Stealthsuit to target creature you control.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Swashbuckler Extraordinaire

When Swashbuckler Extraordinaire enters the battlefield, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Whenever you attack, you may sacrifice one or more Treasures. When you do, up to that many target creatures gain double strike until end of turn.

Expendable Lackey

{1}{U}, Exile Expendable Lackey from your graveyard: Create a 1/1 blue Fish creature token with "This creature can't be blocked." Activate only as a sorcery.

Whirlpool Drake

Flying
When Whirlpool Drake enters the battlefield, shuffle the cards from your hand into your library, then draw that many cards.
When Whirlpool Drake dies, shuffle the cards from your hand into your library, then draw that many cards.

Serum Visions

Spellweaver Eternal

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Afflict 2 (Whenever this creature becomes blocked, defending player loses 2 life.)

Fire Diamond

Fire Diamond enters the battlefield tapped.
{T}: Add {R}.

Crystal Grotto

When Crystal Grotto enters the battlefield, scry 1.
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Neera, Wild Mage

Whenever you cast a spell, you may put it on the bottom of its owner's library. If you do, reveal cards from the top of your library until you reveal a nonland card. You may cast that card without paying its mana cost. Then put all revealed cards not cast this way on the bottom of your library in a random order. This ability triggers only once each turn.

Rhystic Study

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

Barge In

Target attacking creature gets +2/+2 until end of turn. Each attacking non-Human creature gains trample until end of turn.

Mystical Tutor

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

Shiny Impetus

Enchant creature
Enchanted creature gets +2/+2 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
Whenever enchanted creature attacks, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Nimbleclaw Adept

Bigby's Hand — {T}: Untap two other target permanents. Activate only as a sorcery and only once each turn.

Balmor, Battlemage Captain

Flying
Whenever you cast an instant or sorcery spell, creatures you control get +1/+0 and gain trample until end of turn.

Ray of Command

Untap target creature an opponent controls and gain control of it until end of turn. That creature gains haste until end of turn. When you lose control of the creature, tap it.

Island

Wash Out

Return all permanents of the color of your choice to their owners' hands.

Court of Ire

When Court of Ire enters the battlefield, you become the monarch.
At the beginning of your upkeep, Court of Ire deals 2 damage to any target. If you're the monarch, it deals 7 damage instead.

Inundate

Return all nonblue creatures to their owners' hands.

Midnight Clock

{T}: Add {U}.
{2}{U}: Put an hour counter on Midnight Clock.
At the beginning of each upkeep, put an hour counter on Midnight Clock.
When the twelfth hour counter is put on Midnight Clock, shuffle your hand and graveyard into your library, then draw seven cards. Exile Midnight Clock.

Gaseous Form

Enchant creature
Prevent all combat damage that would be dealt to and dealt by enchanted creature.

Ertai's Scorn

This spell costs {U} less to cast if an opponent cast two or more spells this turn.
Counter target spell.

The Locust God

Flying
Whenever you draw a card, create a 1/1 blue and red Insect creature token with flying and haste.
{2}{U}{R}: Draw a card, then discard a card.
When The Locust God dies, return it to its owner's hand at the beginning of the next end step.

Flame Slash

Flame Slash deals 4 damage to target creature.

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.

Dimir Informant

When Dimir Informant enters the battlefield, 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.)

Dazzling Lights

Target creature gets -3/-0 until end of turn.
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.)

Prismari Campus

Prismari Campus enters the battlefield tapped.
{T}: Add {U} or {R}.
{4}, {T}: Scry 1.

Ornithopter

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

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.)

Sage of the Falls

Whenever Sage of the Falls or another non-Human creature enters the battlefield under your control, you may draw a card. If you do, discard a card.

Clever Impersonator

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

Forktail Sweep

Forktail Sweep deals 1 damage to each creature you don't control. (Then exile this card. You may cast the creature later from exile.)

Fang Dragon

Fang Dragon // Forktail Sweep

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.

Turn Aside

Counter target spell that targets a permanent you control.

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.

Bloodfire Mentor

{2}{U}, {T}: Draw a card, then discard a card.

Case the Joint

Draw two cards, then look at the top card of each player's library.

Terramorphic Expanse

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