Naban, Dean of Iteration

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

Threefold Thunderhulk

Threefold Thunderhulk enters with three +1/+1 counters on it.
Whenever Threefold Thunderhulk enters or attacks, create a number of 1/1 colorless Gnome artifact creature tokens equal to its power.
{2}, Sacrifice another artifact: Put a +1/+1 counter on Threefold Thunderhulk.

Nightclub Bouncer

Flash
When Nightclub Bouncer enters, return target nonland permanent an opponent controls to its owner's hand. It perpetually gains "This spell costs {2} more to cast."

Arcane Signet

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

Worn Powerstone

Worn Powerstone enters tapped.
{T}: Add {C}{C}.

Subtlety

Flash
Flying
When Subtlety enters, choose up to one target creature spell or planeswalker spell. Its owner puts it on the top or bottom of their library.
Evoke—Exile a blue card from your hand.

Man-o'-War

When Man-o'-War enters, return target creature to its owner's hand.

Illusionist's Stratagem

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.
Draw a card.

Drownyard Explorers

When Drownyard Explorers enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

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.

Island

Crafty Cutpurse

Flash
When Crafty Cutpurse enters, each token that would be created under an opponent's control this turn is created under your control instead.

Tireless Angler

Whenever an Island or Swamp enters the battlefield under your control, draft a card from Tireless Angler's spellbook.

Salvager of Secrets

When Salvager of Secrets enters, return target instant or sorcery card from your graveyard to your hand.

A-Dungeon Descent

{T}: Add {C}.
{1}, {T}, Tap an untapped legendary creature you control: Venture into the dungeon. Activate only as a sorcery.

Scampering Surveyor

When Scampering Surveyor enters, search your library for a basic land card or Cave card, put it onto the battlefield tapped, then shuffle.

Spyglass Siren

Flying
When Spyglass Siren enters, create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

Mist Raven

Flying
When Mist Raven enters, return target creature to its owner's hand.

Whirler Rogue

When Whirler Rogue enters, create two 1/1 colorless Thopter artifact creature tokens with flying.
Tap two untapped artifacts you control: Target creature can't be blocked this turn.

Outlaw Stitcher

When Outlaw Stitcher enters, create a 2/2 blue and black Zombie Rogue creature token, then put two +1/+1 counters on that token for each spell you've cast this turn other than the first.
Plot {4}{U} (You may pay {4}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Coldsteel Heart

Coldsteel Heart enters tapped.
As Coldsteel Heart enters, choose a color.
{T}: Add one mana of the chosen color.

Landlore Navigator

Whenever Landlore Navigator attacks, create a Map token.
At the beginning of your end step, if two or more artifacts entered under your control this turn, conjure a card named Thieving Magpie onto the battlefield.

Cavalier of Gales

Flying
When Cavalier of Gales enters, draw three cards, then put two cards from your hand on top of your library in any order.
When Cavalier of Gales dies, shuffle it into its owner's library, then scry 2.

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.

Ominous Traveler

When Ominous Traveler enters the battlefield, draft a card from Ominous Traveler's spellbook. That card perpetually gains "You may spend mana as though it were mana of any color to cast this spell" and "When you cast this spell, return a creature named Ominous Traveler you control to its owner's hand."

Meteor Golem

When Meteor Golem enters, destroy target nonland permanent an opponent controls.

Dream Eater

Flash
Flying
When Dream Eater enters, surveil 4. When you do, you may return target nonland permanent an opponent controls to its owner's hand. (To surveil 4, look at the top four cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Sailor of Means

When Sailor of Means enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Golden Argosy

Whenever Golden Argosy attacks, exile each creature that crewed it this turn. Return them to the battlefield tapped under their owner's control at the beginning of the next end step.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Skywriter Djinn

Flying
Domain — When Skywriter Djinn enters, conjure a random card from Skywriter Djinn's spellbook into your hand. Then if you have fewer cards in hand than the number of basic land types among lands you control, repeat this process.

Panharmonicon

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

Displacer Beast

When Displacer Beast enters, venture into the dungeon. (Enter the first room or advance to the next room.)
Displacement — {3}{U}: Return Displacer Beast to its owner's hand.

Mind Stone

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

Aether Channeler

When Aether Channeler 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.

Serum Visionary

When Serum Visionary enters, draw a card, then scry 2.

Waterwind Scout

Flying
When Waterwind Scout enters, create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

Lembas

When Lembas enters, scry 1, then draw a card.
{2}, {T}, Sacrifice Lembas: You gain 3 life.
When Lembas is put into a graveyard from the battlefield, its owner shuffles it into their library.

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.

Alirios, Enraptured

Alirios, Enraptured enters tapped.
Alirios doesn't untap during your untap step if you control a Reflection.
When Alirios enters, create a 3/2 blue Reflection creature token.

The Mightstone and Weakstone

When The Mightstone and Weakstone enters, choose one —
• Draw two cards.
• Target creature gets -5/-5 until end of turn.
{T}: Add {C}{C}. This mana can't be spent to cast nonartifact spells.
(Melds with Urza, Lord Protector.)

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.)

Scholar of the Ages

When Scholar of the Ages enters, return up to two target instant and/or sorcery cards from your graveyard to your hand.

Chromatic Lantern

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

Aviation Pioneer

When Aviation Pioneer enters, create a 1/1 colorless Thopter artifact creature token with flying.

Riddlemaster Sphinx

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Riddlemaster Sphinx enters, you may return target creature an opponent controls to its owner's hand.

A-Circuit Mender

When Circuit Mender enters, you gain 3 life.
When Circuit Mender leaves the battlefield, draw a card.

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Saiba Syphoner

Flash
This spell costs {2} less to cast if there are no instant or sorcery cards in your hand.
When Saiba Syphoner enters, return target instant or sorcery card from your graveyard to your hand.
If Saiba Syphoner would die, shuffle it into your library instead.

Moonsnare Specialist

Ninjutsu {2}{U} ({2}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
When Moonsnare Specialist enters, return up to one target creature to its owner's hand.

Roaming Ghostlight

Flying
When Roaming Ghostlight enters, return up to one target non-Spirit creature to its owner's hand.

Faceless Agent

Changeling
When Faceless Agent enters the battlefield, seek a creature card of the most prevalent creature type in your library. (To seek a card, put one at random from your library into your hand.)

Burdened Aerialist

When Burdened Aerialist enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Whenever you sacrifice a token, Burdened Aerialist gains flying until end of turn.

Exclusion Mage

When Exclusion Mage enters, return target creature an opponent controls to its owner's hand.

Warzone Duplicator

Prototype {3}{U} — 3/3
When Warzone Duplicator enters, return target creature an opponent controls with power less than Warzone Duplicator's power to its owner's hand. If that creature wasn't a token, conjure a duplicate of it into your hand. It perpetually gains "You may spend mana as though it were mana of any color to cast this spell."

Shipwreck Dowser

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Shipwreck Dowser enters, return target instant or sorcery card from your graveyard to your hand.

Cartographer's Companion

When Cartographer's Companion enters, create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

Geistchanneler

When Geistchanneler enters, choose an instant or sorcery card in your hand with mana value 3 or greater. It perpetually gains "This spell costs {2} less to cast."

Eccentric Apprentice

Flying
When Eccentric Apprentice enters, venture into the dungeon. (Enter the first room or advance to the next room.)
At the beginning of combat on your turn, if you've completed a dungeon, up to one target creature becomes a Bird with base power and toughness 1/1 and flying until end of turn.

Scholar of the Lost Trove

Flying
When Scholar of the Lost Trove enters, you may cast target instant, sorcery, or artifact card from your graveyard without paying its mana cost. If an instant or sorcery spell cast this way would be put into your graveyard, exile it instead.

Clone Crafter

When Clone Crafter enters the battlefield, conjure a duplicate of a random creature card from your opponent's library into your hand. It perpetually gains "You may spend mana as though it were mana of any color to cast this spell."

Thought Monitor

Affinity for artifacts
Flying
When Thought Monitor enters, draw two cards.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.