Case of the Ransacked Lab

Instant and sorcery spells you cast cost {1} less to cast.
To solve — You've cast four or more instant and sorcery spells this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Whenever you cast an instant or sorcery spell, draw a card.

Coastal Piracy

Whenever a creature you control deals combat damage to an opponent, you may draw a card.

Aether Tunnel

Enchant creature
Enchanted creature gets +1/+0 and can't be blocked.

Cloudkin Seer

Flying
When this creature enters, draw a card.

Combat Research

Enchant creature
Enchanted creature has "Whenever this creature deals combat damage to a player, draw a card."
As long as enchanted creature is legendary, it gets +1/+1 and has ward {1}. (Whenever enchanted creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)

Mindbreak Trap

If an opponent cast three or more spells this turn, you may pay {0} rather than pay this spell's mana cost.
Exile any number of target spells.

Amphibian Downpour

Flash
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies. Copies become tokens.)
Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1.

Apprentice Wizard

Archaeomancer

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Basilisk Collar

Equipped creature has deathtouch and lifelink. (Any amount of damage it deals to a creature is enough to destroy it. Damage dealt by this creature also causes you to gain that much life.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Cartouche of Knowledge

Enchant creature you control
When this Aura enters, draw a card.
Enchanted creature gets +1/+1 and has flying.

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Talon Gates of Madara

When this land enters, up to one target creature phases out.
{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{4}: Put this card from your hand onto the battlefield.

Altar of the Pantheon

Your devotion to each color and each combination of colors is increased by one.
{T}: Add one mana of any color. If you control a God, a Demigod, or a legendary enchantment, you gain 1 life.

Armory of Iroas

Whenever equipped creature attacks, put a +1/+1 counter on it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Court of Vantress

When this enchantment enters, you become the monarch.
At the beginning of your upkeep, choose up to one other target enchantment or artifact. If you're the monarch, you may create a token that's a copy of it. If you're not the monarch, you may have this enchantment become a copy of it, except it has this ability.

Arcane Signet

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

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Locker Room

Whenever one or more creatures you control deal combat damage to a player, draw a card.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Bottomless Pool

When you unlock this door, return up to one target creature to its owner's hand.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Bottomless Pool // Locker Room

Avarice Amulet

Equipped creature gets +2/+0 and has vigilance and "At the beginning of your upkeep, draw a card."
Whenever equipped creature dies, target opponent gains control of this Equipment.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Crystal Skull, Isu Spyglass

You may look at the top card of your library any time.
You may play historic lands and cast historic spells from the top of your library. (Artifacts, legendaries, and Sagas are historic.)
{T}: Add {U}.

Arcane Laboratory

Each player can't cast more than one spell each turn.

Counterspell

Flare of Denial

You may sacrifice a nontoken blue creature rather than pay this spell's mana cost.
Counter target spell.

Thassa, God of the Sea

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
At the beginning of your upkeep, scry 1.
{1}{U}: Target creature you control can't be blocked this turn.

As Foretold

At the beginning of your upkeep, put a time counter on this enchantment.
Once each turn, you may pay {0} rather than pay the mana cost for a spell you cast with mana value X or less, where X is the number of time counters on this enchantment.

Azure Fleet Admiral

When this creature enters, you become the monarch.
This creature can't be blocked by creatures the monarch controls.

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Chamber of Manipulation

Enchant land
Enchanted land has "{T}, Discard a card: Gain control of target creature until end of turn."

Declaration of Naught

As this enchantment enters, choose a card name.
{U}: Counter target spell with the chosen name.

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Aetherize

Return all attacking creatures to their owner's hand.

Rhystic Study

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

Consecrated Sphinx

Flying
Whenever an opponent draws a card, you may draw two cards.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Sol Ring

Chrome Host Seedshark

Flying
Whenever you cast a noncreature spell, incubate X, where X is that spell's mana value. (Create an Incubator token with X +1/+1 counters on it and "{2}: Transform this token." It transforms into a 0/0 Phyrexian artifact creature.)

Pongify

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

Auramancer's Guise

Enchant creature
Enchanted creature gets +2/+2 for each Aura attached to it and has vigilance.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Ashiok's Erasure

Flash
When this enchantment enters, exile target spell.
Your opponents can't cast spells with the same name as the exiled card.
When this enchantment leaves the battlefield, return the exiled card to its owner's hand.

Soporific Springs

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}.

Sink into Stupor

Return target spell or nonland permanent an opponent controls to its owner's hand.

Sink into Stupor // Soporific Springs

Swan Song

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

Fierce Guardianship

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

Aether Adept

When this creature enters, return target creature to its owner's hand.

Archivist of Gondor

When your commander deals combat damage to a player, if there is no monarch, you become the monarch.
At the beginning of the monarch's end step, that player draws a card.

Champion's Helm

Equipped creature gets +2/+2.
As long as equipped creature is legendary, it has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Counterbalance

Whenever an opponent casts a spell, you may reveal the top card of your library. If you do, counter that spell if it has the same mana value as the revealed card.

Alluring Siren

{T}: Target creature an opponent controls attacks you this turn if able.

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

Court of Cunning

When this enchantment enters, you become the monarch.
At the beginning of your upkeep, any number of target players each mill two cards. If you're the monarch, each of those players mills ten cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Dispel

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard this card: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

Brass Knuckles

When you cast this spell, copy it. (The copy becomes a token.)
Equipped creature has double strike as long as two or more Equipment are attached to it.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Strix Serenade

Counter target artifact, creature, or planeswalker spell. Its controller creates a 2/2 blue Bird creature token with flying.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Cephalid Retainer

{U}{U}: Tap target creature without flying.

Atmosphere Surgeon

Whenever you cast a noncreature spell, put an oil counter on this creature.
Remove an oil counter from this creature: Target creature gains flying until end of turn. Activate only as a sorcery.

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.

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Confounding Conundrum

When this enchantment enters, draw a card.
Whenever a land an opponent controls enters, if that player had another land enter the battlefield under their control this turn, they return a land they control to its owner's hand.

Aether Channeler

When this creature enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.

Azure Mage

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}.

Tishana's Tidebinder

Flash
When this creature enters, counter up to one target activated or triggered ability. If an ability of an artifact, creature, or planeswalker is countered this way, that permanent loses all abilities for as long as this creature remains on the battlefield. (Mana abilities can't be targeted.)

Acquisition Octopus

Whenever this creature or equipped creature deals combat damage to a player, draw a card.
Reconfigure {2} ({2}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Force of Negation

If it's not your turn, you may exile a blue card from your hand rather than pay this spell's mana cost.
Counter target noncreature spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Admiral's Order

Raid — If you attacked this turn, you may pay {U} rather than pay this spell's mana cost.
Counter target spell.

Aarakocra Sneak

Flying
When this creature enters, you take the initiative.

Cemetery Illuminator

Flying
Whenever this creature enters or attacks, exile a card from a graveyard.
You may look at the top card of your library any time.
Once each turn, you may cast a spell from the top of your library if it shares a card type with a card exiled with this creature.

Cloak and Dagger

Equipped creature gets +2/+0 and has shroud. (It can't be the target of spells or abilities.)
Whenever a Rogue creature enters, you may attach this Equipment to it.
Equip {3}

Archmage Ascension

At the beginning of each end step, if you drew two or more cards this turn, you may put a quest counter on this enchantment.
As long as this enchantment has six or more quest counters on it, if you would draw a card, you may instead search your library for a card, put that card into your hand, then shuffle.