Consider

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

Karmic Guide

Flying, protection from black
Echo {3}{W}{W} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Karmic Guide enters, return target creature card from your graveyard to the battlefield.

Thought Vessel

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

Eidolon of Rhetoric

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

Rishadan Cutpurse

When Rishadan Cutpurse enters, each opponent sacrifices a permanent unless they pay {1}.

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Deafening Silence

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

Arcane Signet

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

Aether Barrier

Whenever a player casts a creature spell, that player sacrifices a permanent unless they pay {1}.

Vantress Visions

Copy target activated or triggered ability you control. You may choose new targets for the copy.

Virtue of Knowledge

If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Virtue of Knowledge // Vantress Visions

Thassa, Deep-Dwelling

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of your end step, exile up to one other target creature you control, then return that card to the battlefield under your control.
{3}{U}: Tap another target creature.

Brago, King Eternal

Flying
Whenever Brago, King Eternal deals combat damage to a player, exile any number of target nonland permanents you control, then return those cards to the battlefield under their owner's control.

Elesh Norn, Mother of Machines

Vigilance
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Permanents entering don't cause abilities of permanents your opponents control to trigger.

Winter Orb

As long as Winter Orb is untapped, players can't untap more than one land during their untap steps.

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.

Mana Vault

Mana Vault doesn't untap during your untap step.
At the beginning of your upkeep, you may pay {4}. If you do, untap Mana Vault.
At the beginning of your draw step, if Mana Vault is tapped, it deals 1 damage to you.
{T}: Add {C}{C}{C}.

Island

Arcane Laboratory

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
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.)

Rule of Law

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Grand Arbiter Augustin IV

White spells you cast cost {1} less to cast.
Blue spells you cast cost {1} less to cast.
Spells your opponents cast cost {1} more to cast.

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard Otawara, Soaring City: 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.

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.

Cloudblazer

Flying
When Cloudblazer enters, you gain 2 life and draw two cards.

Command Tower

Mind Stone

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

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Blur

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

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Frozen Aether

Artifacts, creatures, and lands your opponents control enter tapped.

Mana Crypt

At the beginning of your upkeep, flip a coin. If you lose the flip, Mana Crypt deals 3 damage to you.
{T}: Add {C}{C}.

Deadeye Navigator

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Deadeye Navigator is paired with another creature, each of those creatures has "{1}{U}: Exile this creature, then return it to the battlefield under your control."

Soulherder

Whenever a creature is exiled from the battlefield, put a +1/+1 counter on Soulherder.
At the beginning of your end step, you may exile another target creature you control, then return that card to the battlefield under its owner's control.

Mana Tithe

Counter target spell unless its controller pays {1}.

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Reliquary Tower

Eiganjo, Seat of the Empire

{T}: Add {W}.
Channel — {2}{W}, Discard Eiganjo, Seat of the Empire: It deals 4 damage to target attacking or blocking creature. This ability costs {1} less to activate for each legendary creature you control.

Supreme Verdict

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

Deserted Beach

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

Rhystic Study

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

Rishadan Footpad

When Rishadan Footpad enters, each opponent sacrifices a permanent unless they pay {2}.

Prairie Stream

({T}: Add {W} or {U}.)
Prairie Stream enters tapped unless you control two or more basic lands.

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.

Propaganda

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

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.

Ghostly Prison

Fierce Guardianship

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

Sol Ring

Hullbreaker Horror

Flash
This spell can't be countered.
Whenever you cast a spell, choose up to one —
• Return target spell you don't control to its owner's hand.
• Return target nonland permanent to its owner's hand.

Delay

Counter target spell. If the spell is countered this way, exile it with three time counters on it instead of putting it into its owner's graveyard. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

Delney, Streetwise Lookout

Creatures you control with power 2 or less can't be blocked by creatures with power 3 or greater.
If an ability of a creature you control with power 2 or less triggers, that ability triggers an additional time.

Prismatic Vista

{T}, Pay 1 life, Sacrifice Prismatic Vista: Search your library for a basic land card, put it onto the battlefield, then shuffle.

Tundra

Sea of Clouds

Sea of Clouds enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

Plains

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Temporal Distortion

Whenever a creature or land becomes tapped, put an hourglass counter on it.
Each permanent with an hourglass counter on it doesn't untap during its controller's untap step.
At the beginning of each player's upkeep, remove all hourglass counters from permanents that player controls.

Mana Web

Whenever a land an opponent controls is tapped for mana, tap all lands that player controls that could produce any type of mana that land could produce.

Spelltithe Enforcer

Whenever an opponent casts a spell, that player sacrifices a permanent unless they pay {1}.

Rishadan Brigand

Flying
When Rishadan Brigand enters, each opponent sacrifices a permanent unless they pay {3}.
Rishadan Brigand can block only creatures with flying.

Irrigated Farmland

({T}: Add {W} or {U}.)
Irrigated Farmland enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Draining Whelk

Flash
Flying
When Draining Whelk enters, counter target spell. Put X +1/+1 counters on Draining Whelk, where X is that spell's mana value.

Skycloud Expanse

Mystic Gate

{T}: Add {C}.
{W/U}, {T}: Add {W}{W}, {W}{U}, or {U}{U}.

Glacial Fortress

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

Swords to Plowshares

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

Hallowed Fountain

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

Dour Port-Mage

Whenever one or more other creatures you control leave the battlefield without dying, draw a card.
{1}{U}, {T}: Return another target creature you control to its owner's hand.

Azorius Signet

Displacer Kitten

Avoidance — Whenever you cast a noncreature spell, exile up to one target nonland permanent you control, then return that card to the battlefield under its owner's control.

Rishadan Port

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.

Counterspell

Demolition Field

{T}: Add {C}.
{2}, {T}, Sacrifice Demolition Field: Destroy target nonbasic land an opponent controls. That land's controller may search their library for a basic land card, put it onto the battlefield, then shuffle. You may search your library for a basic land card, put it onto the battlefield, then shuffle.

Opposition

Tap an untapped creature you control: Tap target artifact, creature, or land.

Tidespout Tyrant

Flying
Whenever you cast a spell, return target permanent to its owner's hand.

Vanquish the Horde

This spell costs {1} less to cast for each creature on the battlefield.
Destroy all creatures.

Pongify

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