Blue Dragon

Flying
Lightning Breath — When Blue Dragon enters, until your next turn, target creature an opponent controls gets -3/-0, up to one other target creature gets -2/-0, and up to one other target creature gets -1/-0.

Long-Finned Skywhale

Flying
Long-Finned Skywhale can block only creatures with flying.

Island

Skyclave Plunder

Look at the top X cards of your library, where X is three plus the number of creatures in your party. Put three of those cards into your hand and the rest on the bottom of your library in a random order. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Merfolk Sovereign

Other Merfolk creatures you control get +1/+1.
{T}: Target Merfolk creature can't be blocked this turn.

Skyreach Manta

Sunburst (This enters with a +1/+1 counter on it for each color of mana spent to cast it.)
Flying

Merfolk Looter

Kangee, Sky Warden

Flying, vigilance
Whenever Kangee, Sky Warden attacks, attacking creatures with flying get +2/+0 until end of turn.
Whenever Kangee blocks, blocking creatures with flying get +0/+2 until end of turn.

Skyreaping

Skyreaping deals damage to each creature with flying equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)

Sky Diamond

Skyblade's Boon

Enchant creature
Enchanted creature gets +1/+1 and has flying.
{2}{W}: Return Skyblade's Boon to its owner's hand. Activate only if Skyblade's Boon is on the battlefield or in your graveyard.

Abzan Skycaptain

Flying
When Abzan Skycaptain dies, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)

Commander's Sphere

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

Pristine Skywise

Flying
Whenever you cast a noncreature spell, untap Pristine Skywise. It gains protection from the color of your choice until end of turn.

Merfolk Trickster

Flash
When Merfolk Trickster enters, tap target creature an opponent controls. It loses all abilities until end of turn.

Dance of the Skywise

Until end of turn, target creature you control becomes a blue Dragon Illusion with base power and toughness 4/4, loses all abilities, and gains flying.

Merfolk of the Pearl Trident

Kairi, the Swirling Sky

Flying, ward {3}
When Kairi, the Swirling Sky dies, choose one —
• Return any number of target nonland permanents with total mana value 6 or less to their owners' hands.
• Mill six cards, then return up to two instant and/or sorcery cards from your graveyard to your hand.

Skybridge Towers

Skybridge Towers enters tapped.
{T}: Add {W} or {U}.
{2}{W}{U}, {T}, Sacrifice Skybridge Towers: Draw a card.

Skyline Cascade

Skyline Cascade enters tapped.
When Skyline Cascade enters, target creature an opponent controls doesn't untap during its controller's next untap step.
{T}: Add {U}.

Skyboon Evangelist

Flying
When Skyboon Evangelist enters, support 6. (Put a +1/+1 counter on each of up to six other target creatures.)
Whenever a creature with a counter on it attacks one of your opponents, that creature gains flying until end of turn.

Coral Merfolk

Merfolk Windrobber

Flying
Whenever Merfolk Windrobber deals combat damage to a player, that player mills a card. (They put the top card of their library into their graveyard.)
Sacrifice Merfolk Windrobber: Draw a card. Activate only if an opponent has eight or more cards in their graveyard.

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.

Plains

Merfolk Skyscout

Flying
Whenever Merfolk Skyscout attacks or blocks, untap target permanent.

Merfolk Falconer

Flying
Whenever you cast a kicked spell, scry 2.

Seller of Songbirds

When Seller of Songbirds enters, create a 1/1 white Bird creature token with flying.

Skycloud Expanse

Maul of the Skyclaves

When Maul of the Skyclaves enters, attach it to target creature you control.
Equipped creature gets +2/+2 and has flying and first strike.(It deals combat damage before creatures without first strike.)
Equip {2}{W}{W}

Enchant creature
Enchanted creature has flying and "Whenever this creature deals combat damage to a player, venture into the dungeon." (Enter the first room or advance to the next room.)

Mu Yanling, Sky Dancer

+2: Until your next turn, up to one target creature gets -2/-0 and loses flying.
−3: Create a 4/4 blue Elemental Bird creature token with flying.
−8: You get an emblem with "Islands you control have '{T}: Draw a card.'"

Gray Harbor Merfolk

Gray Harbor Merfolk can't be blocked.
Gray Harbor Merfolk gets +2/+0 as long as you control a commander that's a creature or planeswalker.

Skymark Roc

Flying
Whenever Skymark Roc attacks, you may return target creature defending player controls with toughness 2 or less to its owner's hand.

Wishful Merfolk

Defender
{1}{U}: Wishful Merfolk loses defender and becomes a Human until end of turn.

Mystic Skyfish

Whenever you draw your second card each turn, Mystic Skyfish gains flying until end of turn.

Merfolk Wayfinder

Flying
When Merfolk Wayfinder enters, reveal the top three cards of your library. Put all Island cards revealed this way into your hand and the rest on the bottom of your library in any order.

Merfolk Spy

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Merfolk Spy deals combat damage to a player, that player reveals a card at random from their hand.

Merfolk Observer

When Merfolk Observer enters, look at the top card of target player's library.

Sky Crier

Flying, lifelink
{3}{W}: You and target opponent each draw a card.

Sky-Eel School

Flying
When Sky-Eel School enters, draw a card, then discard a card.

Shabraz, the Skyshark

Partner with Brallin, Skyshark Rider
Flying
Whenever you draw a card, put a +1/+1 counter on Shabraz, the Skyshark and you gain 1 life.
{W/U}: Target Human gains flying until end of turn.