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.

Supreme Phantom

Flying
Other Spirits you control get +1/+1.

Call to the Kindred

Enchant creature
At the beginning of your upkeep, you may look at the top five cards of your library. If you do, you may put a creature card that shares a creature type with enchanted creature from among them onto the battlefield, then you put the rest of those cards on the bottom of your library in any order.

Blade of the Bloodchief

Whenever a creature dies, put a +1/+1 counter on equipped creature. If equipped creature is a Vampire, put two +1/+1 counters on it instead.
Equip {1}

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Lookout's Dispersal

This spell costs {1} less to cast if you control a Pirate.
Counter target spell unless its controller pays {4}.

Path of Ancestry

Path of Ancestry enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Sol Ring

Scion of Oona

Flash
Flying
Other Faerie creatures you control get +1/+1.
Other Faeries you control have shroud. (They can't be the targets of spells or abilities.)

Sharpened Pitchfork

Equipped creature has first strike.
As long as equipped creature is a Human, it gets +1/+1.
Equip {1}

Silver-Inlaid Dagger

Equipped creature gets +2/+0.
As long as equipped creature is a Human, it gets an additional +1/+0.
Equip {2}

Animal Sanctuary

{T}: Add {C}.
{2}, {T}: Put a +1/+1 counter on target Bird, Cat, Dog, Goat, Ox, or Snake.

Galerider Sliver

Sliver creatures you control have flying.

Lead-Belly Chimera

Trample
Sacrifice Lead-Belly Chimera: Put a +2/+2 counter on target Chimera creature. It gains trample. (This effect lasts indefinitely.)

Rivendell

Rivendell enters tapped unless you control a legendary creature.
{T}: Add {U}.
{1}{U}, {T}: Scry 2. Activate only if you control a legendary creature.

Compelling Deterrence

Return target nonland permanent to its owner's hand. Then that player discards a card if you control a Zombie.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Bladed Bracers

Equipped creature gets +1/+1.
As long as equipped creature is a Human or an Angel, it has vigilance.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Aquitect's Will

Put a flood counter on target land. That land is an Island in addition to its other types for as long as it has a flood counter on it. If you control a Merfolk, draw a card.

Kopala, Warden of Waves

Spells your opponents cast that target a Merfolk you control cost {2} more to cast.
Abilities your opponents activate that target a Merfolk you control cost {2} more to activate.

Absorb Identity

Return target creature to its owner's hand. You may have Shapeshifters you control become copies of that creature until end of turn.

Obsidian Battle-Axe

Equipped creature gets +2/+1 and has haste.
Whenever a Warrior creature enters, you may attach Obsidian Battle-Axe to it.
Equip {3}

Master of the Pearl Trident

Other Merfolk creatures you control get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Chilling Trap

Target creature gets -4/-0 until end of turn. If you control a Wizard, draw a card.

Unesh, Criosphinx Sovereign

Flying
Sphinx spells you cast cost {2} less to cast.
Whenever Unesh, Criosphinx Sovereign or another Sphinx you control enters, reveal the top four cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Siren's Ruse

Exile target creature you control, then return that card to the battlefield under its owner's control. If a Pirate was exiled this way, draw a card.

Island

Inventor's Goggles

Equipped creature gets +1/+2.
Whenever an Artificer you control enters, you may attach Inventor's Goggles to it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Svyelun of Sea and Sky

Svyelun of Sea and Sky has indestructible as long as you control at least two other Merfolk.
Whenever Svyelun attacks, draw a card.
Other Merfolk you control have ward {1}. (Whenever another Merfolk you control becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)

Jwari Shapeshifter

You may have Jwari Shapeshifter enter as a copy of any Ally creature on the battlefield.

Relic Axe

When Relic Axe enters, attach it to target creature you control.
Equipped creature gets +1/+1. If it's a Warrior, it gets +2/+1 instead.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Mentor's Guidance

When you cast this spell, copy it if you control a planeswalker, Cleric, Druid, Shaman, Warlock, or Wizard.
Scry 1, then draw a card.

Corsair Captain

When this creature enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Other Pirates you control get +1/+1.

Winged Sliver

Sapphire Medallion

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

Mistform Ultimus

Mistform Ultimus is every creature type (even if this card isn't on the battlefield).

Myr Reservoir

{T}: Add {C}{C}. Spend this mana only to cast Myr spells or activate abilities of Myr.
{3}, {T}: Return target Myr card from your graveyard to your hand.

Rooftop Storm

You may pay {0} rather than pay the mana cost for Zombie creature spells you cast.

Lord of the Unreal

Illusion creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Cloak and Dagger

Equipped creature gets +2/+0 and has shroud. (It can't be the target of spells or abilities.)
Whenever a Rogue creature enters, you may attach Cloak and Dagger to it.
Equip {3}

Haven of the Spirit Dragon

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a Dragon creature spell.
{2}, {T}, Sacrifice Haven of the Spirit Dragon: Return target Dragon creature card or Ugin planeswalker card from your graveyard to your hand.

Brass-Talon Chimera

First strike
Sacrifice Brass-Talon Chimera: Put a +2/+2 counter on target Chimera creature. It gains first strike. (This effect lasts indefinitely.)

Tin-Wing Chimera

Flying
Sacrifice Tin-Wing Chimera: Put a +2/+2 counter on target Chimera creature. It gains flying. (This effect lasts indefinitely.)

Veteran's Armaments

Equipped creature has "Whenever this creature attacks or blocks, it gets +1/+1 until end of turn for each attacking creature."
Whenever a Soldier creature enters, you may attach Veteran's Armaments to it.
Equip {2}

Crashing Tide

This spell has flash as long as you control a Merfolk.
Return target creature to its owner's hand.
Draw a card.

Concerted Defense

Counter target noncreature spell unless its controller pays {1} plus an additional {1} for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Griffin Canyon

{T}: Add {C}.
{T}: Untap target Griffin. If it's a creature, it gets +1/+1 until end of turn.

Serpent of Yawning Depths

Krakens, Leviathans, Octopuses, and Serpents you control can't be blocked except by Krakens, Leviathans, Octopuses, and Serpents.

Multiclass Baldric

Equipped creature has lifelink if you control a Cleric, deathtouch if you control a Rogue, haste if you control a Warrior, and flying if you control a Wizard.
As long as you have a full party, prevent all damage that would be dealt to equipped creature.
Equip {2}

Robe of the Archmagi

Whenever equipped creature deals combat damage to a player, you draw that many cards.
Equip {4}
Equip Shaman, Warlock, or Wizard {1}

Stream of Unconsciousness

Lord of Atlantis

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Sky Diamond

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

Diffusion Sliver

Whenever a Sliver creature you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}.

Sea Legs

Flash
Enchant creature
Enchanted creature gets +0/+2 as long as it's a Pirate. Otherwise, it gets -2/-0.

Sage's Dousing

Counter target spell unless its controller pays {3}. If you control a Wizard, draw a card.

Ally Encampment

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast an Ally spell.
{1}, {T}, Sacrifice Ally Encampment: Return target Ally you control to its owner's hand.

Swarmyard

{T}: Add {C}.
{T}: Regenerate target Insect, Rat, Spider, or Squirrel. (The next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Elephant Graveyard

{T}: Add {C}.
{T}: Regenerate target Elephant.

Vodalian Hexcatcher

Flash
Other Merfolk you control get +1/+1.
Sacrifice a Merfolk: Counter target noncreature spell unless its controller pays {1}.

Pirate's Cutlass

When this Equipment enters, attach it to target Pirate you control.
Equipped creature gets +2/+1.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Diviner's Wand

Equipped creature has "Whenever you draw a card, this creature gets +1/+1 and gains flying until end of turn" and "{4}: Draw a card."
Whenever a Wizard creature enters, you may attach Diviner's Wand to it.
Equip {3}

Wizard's Retort

This spell costs {1} less to cast if you control a Wizard.
Counter target spell.

Archway of Innovation

Archway of Innovation enters tapped unless you control an Island.
{T}: Add {U}.
{U}, {T}: The next spell you cast this turn has improvise. (Your artifacts can help cast that spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Riptide Laboratory

{T}: Add {C}.
{1}{U}, {T}: Return target Wizard you control to its owner's hand.

Vedalken Aethermage

Flash (You may cast this spell any time you could cast an instant.)
When Vedalken Aethermage enters, return target Sliver to its owner's hand.
Wizardcycling {3} ({3}, Discard this card: Search your library for a Wizard card, reveal it, put it into your hand, then shuffle.)

Glimpse the Cosmos

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.
As long as you control a Giant, you may cast Glimpse the Cosmos from your graveyard by paying {U} rather than paying its mana cost. If you cast Glimpse the Cosmos this way and it would be put into your graveyard, exile it instead.

Coralhelm Commander

Level up {1} ({1}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 2-3
3/3
Flying
LEVEL 4+
4/4
Flying
Other Merfolk creatures you control get +1/+1.

Merrow Commerce

At the beginning of your end step, untap all Merfolk you control.

Of One Mind

This spell costs {2} less to cast if you control a Human creature and a non-Human creature.
Draw two cards.

Malcolm, Keen-Eyed Navigator

Flying
Whenever one or more Pirates you control deal damage to your opponents, you create a Treasure token for each opponent dealt damage. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Partner (You can have two commanders if both have partner.)

Shadow Sliver

All Sliver creatures have shadow. (They can block or be blocked by only creatures with shadow.)