Have

Scourge of Fleets

When this creature enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Cauldron of Souls

{T}: Choose any number of target creatures. Each of those creatures gains persist until end of turn. (When it dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Panharmonicon

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

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.

Fblthp, the Lost

When Fblthp enters, draw a card. If it entered from your library or was cast from your library, draw two cards instead.
When Fblthp becomes the target of a spell, shuffle Fblthp into its owner's library.

Overwhelmed Apprentice

When this creature enters, each opponent mills two cards. Then you scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Archaeomancer

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

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

Master of Waves

Protection from red
Elemental creatures you control get +1/+1.
When this creature enters, create a number of 1/0 blue Elemental creature tokens equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Cloudkin Seer

Flying
When this creature enters, draw a card.

Nevermaker

Flying
When this creature leaves the battlefield, put target nonland permanent on top of its owner's library.
Evoke {3}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Sea Gate Oracle

When this creature enters, look at the top two cards of your library. Put one of them into your hand and the other on the bottom of your library.

Three Steps Ahead

Spree (Choose one or more additional costs.)
+ {1}{U} — Counter target spell.
+ {3} — Create a token that's a copy of target artifact or creature you control.
+ {2} — Draw two cards, then discard a card.

Annul

Counter target artifact or enchantment spell.

Spellskite

{U/P}: Change a target of target spell or ability to this creature. ({U/P} can be paid with either {U} or 2 life.)

Aether Adept

When this creature enters, return target creature to its owner's hand.

Ponder

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

Thassa's Oracle

When this creature enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Getting

Starfield Vocalist

If a permanent entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Warp {1}{U} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Diluvian Primordial

Flying
When this creature enters, for each opponent, you may cast up to one target instant or sorcery card from that player's graveyard without paying its mana cost. If a spell cast this way would be put into a graveyard, exile it instead.

Circuit Mender

When this creature enters, you gain 2 life.
When this creature leaves the battlefield, draw a card.

Sapphire Medallion

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

Essence Flux

Exile target creature you control, then return that card to the battlefield under its owner's control. If it's a Spirit, put a +1/+1 counter on it.

Familiar's Ruse

As an additional cost to cast this spell, return a creature you control to its owner's hand.
Counter target spell.

Arcane Lighthouse

{T}: Add {C}.
{1}, {T}: Until end of turn, creatures your opponents control lose hexproof and shroud and can't have hexproof or shroud.

Caged Sun

As this artifact enters, choose a color.
Creatures you control of the chosen color get +1/+1.
Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Starwinder

Whenever a creature you control deals combat damage to a player, you may draw that many cards.
Warp {2}{U}{U} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Nyx Lotus

Nyx Lotus enters tapped.
{T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Soporific Springs

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}.

Sink into Stupor

Return target spell or nonland permanent an opponent controls to its owner's hand.

Sink into Stupor // Soporific Springs

Riftwing Cloudskate

Flying
When this creature enters, return target permanent to its owner's hand.
Suspend 3—{1}{U} (Rather than cast this card from your hand, you may pay {1}{U} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

Myriad Landscape

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

Undercover Operative

You may have this creature enter as a copy of any creature on the battlefield, except it enters with a shield counter on it if you control that creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

Man-o'-War

Watcher for Tomorrow

Hideaway 4 (When this creature enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
This creature enters tapped.
When this creature leaves the battlefield, put the exiled card into its owner's hand.

Shadow Puppeteers

Flying, ward {2}
When this creature enters, create two 1/1 black Faerie Rogue creature tokens with flying.
Whenever a creature you control with flying attacks, you may have it become a red Dragon with base power and toughness 4/4 in addition to its other colors and types until end of turn.

Llawan, Cephalid Empress

When Llawan enters, return all blue creatures your opponents control to their owners' hands.
Your opponents can't cast blue creature spells.

Negate

Faerie Seer

Flying
When this creature enters, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard this card: 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.

Harbinger of the Seas

Halimar Depths

This land enters tapped.
When this land enters, look at the top three cards of your library, then put them back in any order.
{T}: Add {U}.

Naban, Dean of Iteration

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

Kefnet's Monument

Blue creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

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.

Detection Tower

{T}: Add {C}.
{1}, {T}: Until end of turn, your opponents and creatures your opponents control with hexproof can be the targets of spells and abilities you control as though they didn't have hexproof.

Island

Mirage Mirror

{2}: This artifact becomes a copy of target artifact, creature, enchantment, or land until end of turn.

Serum Visions

Counterspell

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.

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Mulldrifter

Flying
When this creature 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.)

Aether Channeler

When this creature 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.

Strix Serenade

Counter target artifact, creature, or planeswalker spell. Its controller creates a 2/2 blue Bird creature token with flying.

Meneldor, Swift Savior

Flying
Whenever Meneldor deals combat damage to a player, exile up to one target creature you own, then return it to the battlefield under your control.

Serum Visionary

When this creature enters, draw a card, then scry 2.

March of the Machines

Each noncreature artifact is an artifact creature with power and toughness each equal to its mana value. (Equipment that's a creature can't equip a creature.)

Meteor Golem

When this creature enters, destroy target nonland permanent an opponent controls.

Tishana's Tidebinder

Flash
When this creature enters, counter up to one target activated or triggered ability. If an ability of an artifact, creature, or planeswalker is countered this way, that permanent loses all abilities for as long as this creature remains on the battlefield. (Mana abilities can't be targeted.)

Flare of Denial

You may sacrifice a nontoken blue creature rather than pay this spell's mana cost.
Counter target spell.

Dismiss into Dream

Each creature your opponents control is an Illusion in addition to its other types and has "When this creature becomes the target of a spell or ability, sacrifice it."

Solemn Simulacrum

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

Lonely Sandbar

This land enters tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Reliquary Tower

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

Sol Ring

Willbreaker

Whenever a creature an opponent controls becomes the target of a spell or ability you control, gain control of that creature for as long as you control this creature.

Tome Raider

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.

Mechanozoa

When this creature enters, tap target artifact or creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Warp {2}{U} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Thought Vessel

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.

Agent of Treachery

When this creature enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

High Tide

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

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.

Teferi, Mage of Zhalfir

Flash
Creature cards you own that aren't on the battlefield have flash.
Each opponent can cast spells only any time they could cast a sorcery.

Stern Proctor

When this creature enters, return target artifact or enchantment to its owner's hand.

Peregrine Drake

Flying
When this creature enters, untap up to five lands.

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

Displace

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

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")