Have

Mirror Box

The "legend rule" doesn't apply to permanents you control.
Each legendary creature you control gets +1/+1.
Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.

Hinata, Dawn-Crowned

Flying, trample
Spells you cast cost {1} less to cast for each target.
Spells your opponents cast cost {1} more to cast for each target.

Najal, the Storm Runner

You may cast sorcery spells as though they had flash.
Whenever Najal, the Storm Runner attacks, you may pay {2}. If you do, when you next cast an instant or sorcery spell this turn, copy it. You may choose new targets for the copy.

Sakashima of a Thousand Faces

You may have Sakashima of a Thousand Faces enter the battlefield as a copy of another creature you control, except it has Sakashima of a Thousand Faces's other abilities.
The "legend rule" doesn't apply to permanents you control.
Partner (You can have two commanders if both have partner.)

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate Nightscape Familiar.

Petals of Insight

Look at the top three cards of your library. You may put those cards on the bottom of your library in any order. If you do, return Petals of Insight to its owner's hand. Otherwise, draw three cards.

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Rend Flesh

Aura Shards

Whenever a creature enters the battlefield under your control, you may destroy target artifact or enchantment.

Bounteous Kirin

Flying
Whenever you cast a Spirit or Arcane spell, you may gain life equal to that spell's mana value.

Toils of Night and Day

You may tap or untap target permanent, then you may tap or untap another target permanent.

Peer Through Depths

Look at the top five cards of your library. You may reveal an instant or sorcery card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Psychic Puppetry

You may tap or untap target permanent.
Splice onto Arcane {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.)

Drogskol Captain

Flying
Other Spirit creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Swarm Intelligence

Whenever you cast an instant or sorcery spell, you may copy that spell. You may choose new targets for the copy.

Long-Forgotten Gohei

Arcane spells you cast cost {1} less to cast.
Spirit creatures you control get +1/+1.

Eye of Nowhere

Return target permanent to its owner's hand.

Haughty Djinn

Flying
Haughty Djinn's power is equal to the number of instant and sorcery cards in your graveyard.
Instant and sorcery spells you cast cost {1} less to cast.

Thunderscape Familiar

First strike
Black spells and green spells you cast cost {1} less to cast.

Hana Kami

{1}{G}, Sacrifice Hana Kami: Return target Arcane card from your graveyard to your hand.

Ribbons of the Reikai

Solve the Equation

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Congregation at Dawn

Search your library for up to three creature cards, reveal them, then shuffle and put those cards on top in any order.

Soulless Revival

Return target creature card from your graveyard to your hand.
Splice onto Arcane {1}{B} (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.)

Terashi's Grasp

Destroy target artifact or enchantment. You gain life equal to its mana value.

Oyobi, Who Split the Heavens

Flying
Whenever you cast a Spirit or Arcane spell, create a 3/3 white Spirit creature token with flying.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless enters the battlefield, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Sire of the Storm

Flying
Whenever you cast a Spirit or Arcane spell, you may draw a card.

Otherworldly Journey

Exile target creature. At the beginning of the next end step, return that card to the battlefield under its owner's control with a +1/+1 counter on it.

Evermind

(Nonexistent mana costs can't be paid.)
Draw a card.
Splice onto Arcane {1}{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.)

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Eerie Procession

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

Tiller Engine

Whenever a land enters the battlefield tapped and under your control, choose one —
• Untap that land.
• Tap target nonland permanent an opponent controls.

Consuming Vortex

Return target creature to its owner's hand.
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.)

Spiritual Visit

Create a 1/1 colorless Spirit creature token.
Splice onto Arcane {W} (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.)

Ire of Kaminari

Ire of Kaminari deals damage to any target equal to the number of Arcane cards in your graveyard.

Spiraling Embers

Spiraling Embers deals damage to any target equal to the number of cards in your hand.

Blessed Breath

Target creature you control gains protection from the color of your choice until end of turn.
Splice onto Arcane {W} (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.)

Patron of the Moon

Moonfolk offering (You may cast this card any time you could cast an instant by sacrificing a Moonfolk and paying the difference in mana costs between this and the sacrificed Moonfolk. Mana cost includes color.)
Flying
{1}: Put up to two land cards from your hand onto the battlefield tapped.

Sift Through Sands

Draw two cards, then discard a card.
If you've cast a spell named Peer Through Depths and a spell named Reach Through Mists this turn, you may search your library for a card named The Unspeakable, put it onto the battlefield, then shuffle.

Thousand-Year Storm

Whenever you cast an instant or sorcery spell, copy it for each other instant and sorcery spell you've cast before it this turn. You may choose new targets for the copies.

Glacial Ray

Glacial Ray deals 2 damage to any target.
Splice onto Arcane {1}{R} (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.)

Elder Pine of Jukai

Whenever you cast a Spirit or Arcane spell, reveal the top three cards of your library. Put all land cards revealed this way into your hand and the rest on the bottom of your library in any order.
Soulshift 2 (When this creature dies, you may return target Spirit card with mana value 2 or less from your graveyard to your hand.)

Kami of Whispered Hopes

If one or more +1/+1 counters would be put on a permanent you control, that many plus one +1/+1 counters are put on that permanent instead.
{T}: Add X mana of any one color, where X is Kami of Whispered Hopes's power.

Amulet of Vigor

Whenever a permanent enters the battlefield tapped and under your control, untap it.

Drift of Phantasms

Defender (This creature can't attack.)
Flying
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Loam Dweller

Whenever you cast a Spirit or Arcane spell, you may put a land card from your hand onto the battlefield tapped.

Sunscape Familiar

Defender (This creature can't attack.)
Green spells and blue spells you cast cost {1} less to cast.

Unnatural Speed

Target creature gains haste until end of turn.

Wear Away

Destroy target artifact or enchantment.
Splice onto Arcane {3}{G} (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.)

Briarknit Kami

Whenever you cast a Spirit or Arcane spell, put a +1/+1 counter on target creature.

Mindsplice Apparatus

Flash
At the beginning of your upkeep, put an oil counter on Mindsplice Apparatus.
Instant and sorcery spells you cast cost {1} less to cast for each oil counter on Mindsplice Apparatus.

Ideas Unbound

Draw three cards. Discard three cards at the beginning of the next end step.

Veil of Secrecy

Target creature gains shroud until end of turn and can't be blocked this turn. (A creature with shroud can't be the target of spells or abilities.)
Splice onto Arcane—Return a blue creature you control to its owner's hand. (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.)

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

First Volley

First Volley deals 1 damage to target creature and 1 damage to that creature's controller.

Petalmane Baku

Whenever you cast a Spirit or Arcane spell, you may put a ki counter on Petalmane Baku.
{1}, Remove X ki counters from Petalmane Baku: Add X mana of any one color.

Reach Through Mists

Orvar, the All-Form

Changeling
Whenever you cast an instant or sorcery spell, if it targets one or more other permanents you control, create a token that's a copy of one of those permanents.
When a spell or ability an opponent controls causes you to discard this card, create a token that's a copy of target permanent.

Reweave

Target permanent's controller sacrifices it. If the player does, they reveal cards from the top of their library until they reveal a permanent card that shares a card type with the sacrificed permanent, put that card onto the battlefield, then shuffle.
Splice onto Arcane {2}{U}{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.)

Stream of Consciousness

Target player shuffles up to four target cards from their graveyard into their library.

Quiet Purity

Tomorrow, Azami's Familiar

If you would draw a card, look at the top three cards of your library instead. Put one of those cards into your hand and the rest on the bottom of your library in any order.

Choice of Damnations

Target opponent chooses a number. You may have that player lose that much life. If you don't, that player sacrifices all but that many permanents.

Wizards of Thay

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Instant and sorcery spells you cast cost {1} less to cast.
You may cast sorcery spells as though they had flash.