Seething Landscape

{T}: Add {C}.
{T}, Sacrifice this land: Search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.
Cycling {U}{B}{R} ({U}{B}{R}, Discard this card: Draw a card.)

Man-o'-War

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

City of Brass

Whenever this land becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any 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.)

Thassa, God of the Sea

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
At the beginning of your upkeep, scry 1.
{1}{U}: Target creature you control can't be blocked this turn.

Hazel's Brewmaster

Menace
Whenever this creature enters or attacks, exile up to one target card from a graveyard and create a Food token.
Foods you control have all activated abilities of all creature cards exiled with this creature.

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Maeve, Insidious Singer

{2}{U}: Goad target creature. Whenever that creature attacks one of your opponents this turn, you draw a card. (A goaded creature attacks each combat if able and attacks a player other than you if able, until your next turn.)

Island

Confiscate

Enchant permanent
You control enchanted permanent.

Barktooth Warbeard

Butcher's Cleaver

Equipped creature gets +3/+0.
As long as equipped creature is a Human, it has lifelink.
Equip {3}

Sol Ring

Seething Song

Steam Vents

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

Witch's Cauldron

{1}{B}, {T}, Sacrifice a creature: You gain 1 life and draw a card.

Dockside Chef

{1}{B}, Sacrifice an artifact or creature: Draw a card.

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

Voracious Greatshark

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, counter target artifact or creature spell.

Rotisserie Elemental

Menace
Whenever this creature deals combat damage to a player, put a skewer counter on this creature. Then you may sacrifice it. If you do, exile the top X cards of your library, where X is the number of skewer counters on this creature. You may play those cards this turn.

Sulfur Falls

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

Giant Shark

This creature can't attack unless defending player controls an Island.
Whenever this creature blocks or becomes blocked by a creature that has been dealt damage this turn, this creature gets +2/+0 and gains trample until end of turn.
When you control no Islands, sacrifice this creature.

The Underworld Cookbook

{T}, Discard a card: Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
{4}, {T}, Sacrifice this artifact: Return target creature card from your graveyard to your hand.

Aboleth Spawn

Flash
Ward {2}
Probing Telepathy — Whenever a creature entering under an opponent's control causes a triggered ability of that creature to trigger, you may copy that ability. You may choose new targets for the copy.

Walking Sponge

{T}: Target creature loses your choice of flying, first strike, or trample until end of turn.

Ichthyomorphosis

Enchant creature
Enchanted creature loses all abilities and is a blue Fish with base power and toughness 0/1.

Trusty Machete

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Feast of Succession

All creatures get -4/-4 until end of turn. You become the monarch.

Fellwar Stone

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

Commander's Sphere

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

Vivid Flying Fish

This creature has flying as long as it's attacking. (It can't be blocked except by creatures with flying or reach.)

Sigiled Starfish

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

Dan Lewis

Noncreature, non-Equipment artifacts you control are Equipment in addition to their other types and have "Equipped creature gets +1/+0" and equip {1}.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Tetsuo Umezawa

Tetsuo Umezawa can't be the target of Aura spells.
{U}{B}{B}{R}, {T}: Destroy target tapped or blocking creature.

Master of the Feast

Flying
At the beginning of your upkeep, each opponent draws a card.

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Dragonskull Summit

This land enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

High Tide

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

Asmoranomardicadaistinaculdacar

As long as you've discarded a card this turn, you may pay {B/R} to cast this spell.
When Asmoranomardicadaistinaculdacar enters, you may search your library for a card named The Underworld Cookbook, reveal it, put it into your hand, then shuffle.
Sacrifice two Foods: Target creature deals 6 damage to itself.

Syr Ginger, the Meal Ender

Syr Ginger has trample, hexproof, and haste as long as an opponent controls a planeswalker.
Whenever another artifact you control is put into a graveyard from the battlefield, put a +1/+1 counter on Syr Ginger and scry 1.
{2}, {T}, Sacrifice Syr Ginger: You gain life equal to its power.

Xander's Lounge

({T}: Add {U}, {B}, or {R}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Greed

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Mystic Remora

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Chromatic Lantern

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

Crush of Tentacles

Surge {3}{U}{U} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Return all nonland permanents to their owners' hands. If this spell's surge cost was paid, create an 8/8 blue Octopus creature token.

Fishing Pole

Equipped creature has "{1}, {T}, Tap Fishing Pole: Put a bait counter on Fishing Pole."
Whenever equipped creature becomes untapped, remove a bait counter from this Equipment. If you do, create a 1/1 blue Fish creature token.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Blood Crypt

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

Giant Oyster

You may choose not to untap this creature during your untap step.
{T}: For as long as this creature remains tapped, target tapped creature doesn't untap during its controller's untap step, and at the beginning of each of your draw steps, put a -1/-1 counter on that creature. When this creature leaves the battlefield or becomes untapped, remove all -1/-1 counters from the creature.

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.

Watery Grave

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

Red Herring

Haste
This creature attacks each combat if able.
{2}, Sacrifice this creature: Draw a card.

Lembas

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

Sauté

Witch's Oven

{T}, Sacrifice a creature: Create a Food token. If the sacrificed creature's toughness was 4 or greater, create two Food tokens instead. (They're artifacts with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Windrider Eel

Flying
Landfall — Whenever a land you control enters, this creature gets +2/+2 until end of turn.

Abyssal Hunter

{B}, {T}: Tap target creature. This creature deals damage equal to its power to that creature.

Peek

Look at target player's hand.
Draw a card.

Red Death, Shipwrecker

Alluring Eyes — {T}: Goad target creature an opponent controls. That player draws a card. You add {R}. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Crumbling Necropolis

This land enters tapped.
{T}: Add {U}, {B}, or {R}.

Exotic Orchard

Arcane Signet

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

Morphic Pool

This land enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

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.)

Swamp

Giant Octopus

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Chasm Skulker

Whenever you draw a card, put a +1/+1 counter on this creature.
When this creature dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on this creature. (They can't be blocked as long as defending player controls an Island.)

Bladebrand

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

Mountain

Sleep with the Fishes

Enchant creature
When this Aura enters, tap enchanted creature and you create a 1/1 blue Fish creature token with "This token can't be blocked."
Enchanted creature doesn't untap during its controller's untap step.

Gingerbrute

Haste (This creature can attack and {T} as soon as it comes under your control.)
{1}: This creature can't be blocked this turn except by creatures with haste.
{2}, {T}, Sacrifice this creature: You gain 3 life.

Command Tower

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Jori En, Ruin Diver

Whenever you cast your second spell each turn, draw a card.

Giant's Skewer

Equipped creature gets +2/+1.
Whenever equipped creature deals combat damage to a creature, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Sinister Starfish

{T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)