Have

Terrain Generator

{T}: Add {C}.
{2}, {T}: You may put a basic land card from your hand onto the battlefield tapped.

Mass Manipulation

Gain control of X target creatures and/or planeswalkers.

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.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Counterspell

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Academy Elite

Academy Elite enters with X +1/+1 counters on it, where X is the number of instant and sorcery cards in all graveyards.
{2}{U}, Remove a +1/+1 counter from Academy Elite: Draw a card, then discard a card.

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.

Kenton's Suggested

Enhanced Awareness

Venser's Journal

You have no maximum hand size.
At the beginning of your upkeep, you gain 1 life for each card in your hand.

Memorial to Genius

Memorial to Genius enters tapped.
{T}: Add {U}.
{4}{U}, {T}, Sacrifice Memorial to Genius: Draw two cards.

Elminster's Simulacrum

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

Pull from Tomorrow

Awoken Horror

When this creature transforms into Awoken Horror, return all non-Horror creatures to their owners' hands.

Thing in the Ice

Defender
Thing in the Ice enters with four ice counters on it.
Whenever you cast an instant or sorcery spell, remove an ice counter from Thing in the Ice. Then if it has no ice counters on it, transform it.

Thing in the Ice // Awoken Horror

Oona's Grace

Target player draws a card.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Getting

Wavebreak Hippocamp

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

Escape Detection

Freerunning—Return a blue creature you control to its owner's hand. (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
Return target creature to its owner's hand.
Draw a card.

Mockingbird

Flying
You may have Mockingbird enter as a copy of any creature on the battlefield with mana value less than or equal to the amount of mana spent to cast Mockingbird, except it's a Bird in addition to its other types and it has flying.

Primal Wellspring

(Transforms from Primal Amulet.)
{T}: Add one mana of any color. When that mana is spent to cast an instant or sorcery spell, copy that spell and you may choose new targets for the copy.

Primal Amulet

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, put a charge counter on Primal Amulet. Then if there are four or more charge counters on it, you may remove those counters and transform it.

Primal Amulet // Primal Wellspring

Unwind

Counter target noncreature spell. Untap up to three lands.

Thirst for Discovery

Draw three cards. Then discard two cards unless you discard a basic land card.

Chemister's Insight

Draw two cards.
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.)

Proft's Eidetic Memory

When Proft's Eidetic Memory enters, draw a card.
You have no maximum hand size.
At the beginning of combat on your turn, if you've drawn more than one card this turn, put X +1/+1 counters on target creature you control, where X is the number of cards you've drawn this turn minus one.

Don't Have

Sublime Epiphany

Choose one or more —
• Counter target spell.
• Counter target activated or triggered ability.
• Return target nonland permanent to its owner's hand.
• Create a token that's a copy of target creature you control.
• Target player draws a card.

Myriad Landscape

Myriad Landscape enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

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.

Soaring Seacliff

Soaring Seacliff enters tapped.
When Soaring Seacliff enters, target creature gains flying until end of turn.
{T}: Add {U}.

Silver Shroud Costume

Flash
When Silver Shroud Costume enters, attach it to target creature you control. That creature gains shroud until end of turn. (It can't be the target of spells or abilities.)
Equipped creature can't be blocked.
Equip {3}

Clone

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

Archaeomancer

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

Planar Incision

Exile target artifact or creature, then return it to the battlefield under its owner's control with a +1/+1 counter on it.

Blur

Exile target creature you control, then return that card to the battlefield under its owner's control.
Draw a card.

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Wishing Well

{T}: Put a coin counter on Wishing Well. When you do, you may cast target instant or sorcery card with mana value equal to the number of coin counters on Wishing Well from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead. Activate only as a sorcery.

Eluge, the Shoreless Sea

Eluge's power and toughness are each equal to the number of Islands you control.
Whenever Eluge enters or attacks, put a flood counter on target land. It's an Island in addition to its other types for as long as it has a flood counter on it.
The first instant or sorcery spell you cast each turn costs {U} (or {1}) less to cast for each land you control with a flood counter on it.

Keep Watch

Archmage's Charm

Choose one —
• Counter target spell.
• Target player draws two cards.
• Gain control of target nonland permanent with mana value 1 or less.

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.

Mind Unbound

At the beginning of your upkeep, put a lore counter on Mind Unbound, then draw a card for each lore counter on Mind Unbound.

Jace's Sanctum

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, scry 1.

Brainstorm

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

Lonnie's Suggested Swaps

Thunderclap Drake

Flying
Instant and sorcery spells you cast cost {1} less to cast.
{2}{U}, Sacrifice Thunderclap Drake: When you next cast an instant or sorcery spell this turn, copy it for each time you've cast your commander from the command zone this game. You may choose new targets for the copies.

Blessed Reincarnation

Exile target creature an opponent controls. That player reveals cards from the top of their library until a creature card is revealed. The player puts that card onto the battlefield, then shuffles the rest into their library.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Spell Rupture

Counter target spell unless its controller pays {X}, where X is the greatest power among creatures you control.

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Kaito, Cunning Infiltrator

Whenever a creature you control deals combat damage to a player, put a loyalty counter on Kaito.
+1: Up to one target creature you control can't be blocked this turn. Draw a card, then discard a card.
−2: Create a 2/1 blue Ninja creature token.
−9: You get an emblem with "Whenever a player casts a spell, you create a 2/1 blue Ninja creature token."

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Castle Vantress

Castle Vantress enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Archmage Emeritus

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

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Thundertrap Trainer

Offspring {4} (You may pay an additional {4} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
When this creature enters, look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

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.

Aetherize

Return all attacking creatures to their owner's hand.

Brain in a Jar

{1}, {T}: Put a charge counter on Brain in a Jar, then you may cast an instant or sorcery spell with mana value equal to the number of charge counters on Brain in a Jar from your hand without paying its mana cost.
{3}, {T}, Remove X charge counters from Brain in a Jar: Scry X.

Karn's Temporal Sundering

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Target player takes an extra turn after this one. Return up to one target nonland permanent to its owner's hand. Exile Karn's Temporal Sundering.

Remand

Counter target spell. If that spell is countered this way, put it into its owner's hand instead of into that player's graveyard.
Draw a card.

Invoke the Winds

Gain control of target artifact or creature. Untap it.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Frantic Search

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

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Teferi's Time Twist

Exile target permanent you control. Return that card to the battlefield under its owner's control at the beginning of the next end step. If it enters as a creature, it enters with an additional +1/+1 counter on it.

Epiphany at the Drownyard

Reveal the top X plus one cards of your library and separate them into two piles. An opponent chooses one of those piles. Put that pile into your hand and the other into your graveyard.

Kraken's Eye

Whenever a player casts a blue spell, you may gain 1 life.

Temple of the False God

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

Cephalid Coliseum

{T}: Add {U}. Cephalid Coliseum deals 1 damage to you.
Threshold — {U}, {T}, Sacrifice Cephalid Coliseum: Target player draws three cards, then discards three cards. Activate only if seven or more cards are in your graveyard.

Scavenger Grounds

{T}: Add {C}.
{2}, {T}, Sacrifice a Desert: Exile all graveyards.

Enter the Enigma

Target creature can't be blocked this turn.
Draw a card.

Dominate

Gain control of target creature with mana value X or less.

Island

Reliquary Tower

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

Thought Vessel

Arcane Laboratory

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

Energy Flux

All artifacts have "At the beginning of your upkeep, sacrifice this artifact unless you pay {2}."

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Negate

Arcane Melee

Instant and sorcery spells cost {2} less to cast.

Spell Swindle

Counter target spell. Create X Treasure tokens, where X is that spell's mana value. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Mystic Confluence

Choose three. You may choose the same mode more than once.
• Counter target spell unless its controller pays {3}.
• Return target creature to its owner's hand.
• Draw a card.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Trail of Evidence

Whenever you cast an instant or sorcery spell, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Mana Breach

Whenever a player casts a spell, that player returns a land they control to its owner's hand.

Stolen Identity

Create a token that's a copy of target artifact or creature.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Flow of Ideas

Compulsive Research

Target player draws three cards. Then that player discards two cards unless they discard a land card.

Sunken Palace

Sunken Palace enters tapped.
{T}: Add {U}.
{1}{U}, {T}, Exile seven cards from your graveyard: Add {U}. When you spend this mana to cast a spell or activate an ability, copy that spell or ability. You may choose new targets for the copy. (Mana abilities can't be copied.)

Rhystic Study

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

Gossip's Talent

(Gain the next level as a sorcery to add its ability.)
Whenever a creature you control enters, surveil 1.
{1}{U}: Level 2
Whenever you attack, target attacking creature with power 3 or less can't be blocked this turn.
{3}{U}: Level 3
Whenever a creature you control deals combat damage to a player, you may exile it, then return it to the battlefield under its owner's control.

Reverse the Polarity

Choose one —
• Counter all other spells.
• Switch each creature's power and toughness until end of turn.
• Creatures can't be blocked this turn.

The Mirari Conjecture

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Return target instant card from your graveyard to your hand.
II — Return target sorcery card from your graveyard to your hand.
III — Until end of turn, whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy.

Displacement Wave

Return all nonland permanents with mana value X or less to their owners' hands.

Rewind

Counter target spell. Untap up to four lands.

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.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Don't Make a Sound

Counter target spell unless its controller pays {2}. If they do, 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.)

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Short Bow

Equipped creature gets +1/+1 and has vigilance and reach.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)