Consider

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

Fervor

Creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Reliquary Tower

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

Kykar, Wind's Fury

Flying
Whenever you cast a noncreature spell, create a 1/1 white Spirit creature token with flying.
Sacrifice a Spirit: Add {R}.

Blazing Archon

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

Zetalpa, Primal Dawn

Flying, double strike, vigilance, trample, indestructible

Dovin's Veto

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

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Narset's Reversal

Copy target instant or sorcery spell, then return it to its owner's hand. You may choose new targets for the copy.

Synthetic Destiny

Exile all creatures you control. At the beginning of the next end step, reveal cards from the top of your library until you reveal that many creature cards, put all creature cards revealed this way onto the battlefield, then shuffle the rest of the revealed cards into your library.

Island

Medomai the Ageless

Flying
Whenever Medomai the Ageless deals combat damage to a player, take an extra turn after this one.
Medomai the Ageless can't attack during extra turns.

Glasspool Shore

Glasspool Shore enters tapped.
{T}: Add {U}.

Glasspool Mimic

You may have Glasspool Mimic enter as a copy of a creature you control, except it's a Shapeshifter Rogue in addition to its other types.

Glasspool Mimic // Glasspool Shore

Sacred Foundry

({T}: Add {R} or {W}.)
As Sacred Foundry enters, you may pay 2 life. If you don't, it enters tapped.

Valakut Stoneforge

Valakut Stoneforge enters tapped.
{T}: Add {R}.

Valakut Awakening

Put any number of cards from your hand on the bottom of your library, then draw that many cards plus one.

Valakut Awakening // Valakut Stoneforge

Perilous Research

Draw two cards, then sacrifice a permanent.

Propaganda

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

Raugrin Triome

({T}: Add {U}, {R}, or {W}.)
Raugrin Triome enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Stormcarved Coast

Stormcarved Coast enters tapped unless you control two or more other lands.
{T}: Add {U} or {R}.

Deserted Beach

Deserted Beach enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

Counterspell

Mass Polymorph

Exile all creatures you control, then reveal cards from the top of your library until you reveal that many creature cards. Put all creature cards revealed this way onto the battlefield, then shuffle the rest of the revealed cards into your library.

Arcane Signet

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

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.)

Command Tower

Expedite

Target creature gains haste until end of turn.
Draw a card.

Gitaxian Probe

({U/P} can be paid with either {U} or 2 life.)
Look at target player's hand.
Draw a card.

Serra's Emissary

Flying
As Serra's Emissary enters, choose a card type.
You and creatures you control have protection from the chosen card type.

Divine Visitation

If one or more creature tokens would be created under your control, that many 4/4 white Angel creature tokens with flying and vigilance are created instead.

Transmogrify

Exile target creature. That creature's controller reveals cards from the top of their library until they reveal a creature card. That player puts that card onto the battlefield, then shuffles the rest into their library.

Memory Deluge

Look at the top X cards of your library, where X is the amount of mana spent to cast this spell. Put two of them into your hand and the rest on the bottom of your library in a random order.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Lazotep Plating

Amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)
You and permanents you control gain hexproof until end of turn. (You and they can't be the targets of spells or abilities your opponents control.)

Training Center

Training Center enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Brainstorm

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

Mystic Monastery

Mystic Monastery enters tapped.
{T}: Add {U}, {R}, or {W}.

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.

Polymorph

Destroy target creature. It can't be regenerated. Its controller reveals cards from the top of their library until they reveal a creature card. The player puts that card onto the battlefield, then shuffles all other cards revealed this way into their library.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

See Beyond

Draw two cards, then shuffle a card from your hand into your library.

Saheeli, Sublime Artificer

Whenever you cast a noncreature spell, create a 1/1 colorless Servo artifact creature token.
−2: Target artifact you control becomes a copy of another target artifact or creature you control until end of turn, except it's an artifact in addition to its other types.

Indomitable Creativity

Destroy X target artifacts and/or creatures. For each permanent destroyed this way, its controller reveals cards from the top of their library until an artifact or creature card is revealed and exiles that card. Those players put the exiled cards onto the battlefield, then shuffle.

Proteus Staff

{2}{U}, {T}: Put target creature on the bottom of its owner's library. That creature's controller reveals cards from the top of their library until they reveal a creature card. The player puts that card onto the battlefield and the rest on the bottom of their library in any order. Activate only as a sorcery.

Jin-Gitaxias, Progress Tyrant

Whenever you cast an artifact, instant, or sorcery spell, copy that spell. You may choose new targets for the copy. This ability triggers only once each turn. (A copy of a permanent spell becomes a token.)
Whenever an opponent casts an artifact, instant, or sorcery spell, counter that spell. This ability triggers only once each turn.

Anointed Procession

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Sorcerer Class

(Gain the next level as a sorcery to add its ability.)
When Sorcerer Class enters, draw two cards, then discard two cards.
{U}{R}: Level 2
Creatures you control have "{T}: Add {U} or {R}. Spend this mana only to cast an instant or sorcery spell or to gain a Class level."
{3}{U}{R}: Level 3
Whenever you cast an instant or sorcery spell, that spell deals damage to each opponent equal to the number of instant and sorcery spells you've cast this turn.

Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Mountain

Pillarverge Pathway

Needleverge Pathway

Needleverge Pathway // Pillarverge Pathway

Urabrask the Hidden

Creatures you control have haste.
Creatures your opponents control enter tapped.

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

Counterflux

This spell can't be countered.
Counter target spell you don't control.
Overload {1}{U}{U}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Serum Visions

Aurelia, the Warleader

Flying, vigilance, haste
Whenever Aurelia attacks for the first time each turn, untap all creatures you control. After this phase, there is an additional combat phase.

Clever Impersonator

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

Mistgate Pathway

Hengegate Pathway

Hengegate Pathway // Mistgate Pathway

Sundown Pass

Sundown Pass enters tapped unless you control two or more other lands.
{T}: Add {R} or {W}.

Supreme Verdict

This spell can't be countered.
Destroy all creatures.

Elesh Norn, Grand Cenobite

Vigilance
Other creatures you control get +2/+2.
Creatures your opponents control get -2/-2.

Drawn from Dreams

Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in a random order.

Plains

Blightsteel Colossus

Trample, infect, indestructible
If Blightsteel Colossus would be put into a graveyard from anywhere, reveal Blightsteel Colossus and shuffle it into its owner's library instead.

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.

Sol Ring

Ghostly Prison

Hallowed Burial

Put all creatures on the bottom of their owners' libraries.

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. Talisman of Creativity deals 1 damage to you.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Lavaglide Pathway

Riverglide Pathway

Riverglide Pathway // Lavaglide Pathway

Reality Scramble

Put target permanent you own on the bottom of your library. Reveal cards from the top of your library until you reveal a card that shares a card type with that permanent. Put that card onto the battlefield and the rest on the bottom of your library in a random order.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Gisela, Blade of Goldnight

Flying, first strike
If a source would deal damage to an opponent or a permanent an opponent controls, that source deals double that damage to that player or permanent instead.
If a source would deal damage to you or a permanent you control, prevent half that damage, rounded up.

Steam Vents

({T}: Add {U} or {R}.)
As Steam Vents enters, you may pay 2 life. If you don't, it enters tapped.

Wash Away

Cleave {1}{U}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Counter target spell [that wasn't cast from its owner's hand].

Whirlwind of Thought

Whenever you cast a noncreature spell, draw a card.

Generous Gift

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

Exotic Orchard

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

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Swords to Plowshares

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

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. Talisman of Conviction deals 1 damage to you.

Archaeomancer's Map

When Archaeomancer's Map enters, search your library for up to two basic Plains cards, reveal them, put them into your hand, then shuffle.
Whenever a land an opponent controls enters, if that player controls more lands than you, you may put a land card from your hand onto the battlefield.

Rhystic Study

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