Ishai, Ojutai Dragonspeaker

Flying
Whenever an opponent casts a spell, put a +1/+1 counter on Ishai.
Partner (You can have two commanders if both have partner.)

Biomass Mutation

Creatures you control have base power and toughness X/X until end of turn.

Eyes in the Skies

Create a 1/1 white Bird creature token with flying, then populate. (Create a token that's a copy of a creature token you control.)

Echoing Equation

Choose target creature you control. Each other creature you control becomes a copy of it until end of turn, except those creatures aren't legendary.

Augmenter Pugilist

Trample
As long as you control eight or more lands, this creature gets +5/+5.

Augmenter Pugilist // Echoing Equation

Call

Create four 1/1 white Bird creature tokens with flying.
Fuse (You may cast one or both halves of this card from your hand.)

Beck

Whenever a creature enters this turn, you may draw a card.
Fuse (You may cast one or both halves of this card from your hand.)

Beck // Call

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.

Rimewood Falls

({T}: Add {G} or {U}.)
This land enters tapped.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Airborne Aid

Draw a card for each Bird on the battlefield.

Messenger Falcons

Flying
When this creature enters, draw a card.

Sakura-Tribe Elder

Sacrifice this creature: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Selesnya Sanctuary

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {G}{W}.

Tome of Legends

This artifact enters with a page counter on it.
Whenever your commander enters or attacks, put a page counter on this artifact.
{1}, {T}, Remove a page counter from this artifact: Draw a card.

Forest

Fountainport Bell

When this artifact enters, you may search your library for a basic land card, reveal it, then shuffle and put that card on top.
{1}, Sacrifice this artifact: Draw a card.

Expedition Map

{2}, {T}, Sacrifice this artifact: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Krosan Verge

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for a Forest card and a Plains card, put them onto the battlefield tapped, then shuffle.

Cloudchaser Kestrel

Flying
When this creature enters, destroy target enchantment.
{W}: Target permanent becomes white until end of turn.

Brushland

{T}: Add {C}.
{T}: Add {G} or {W}. This land deals 1 damage to you.

Winged Portent

Cleave {4}{G}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Draw a card for each creature you control [with flying].

Suntail Hawk

Aerial Extortionist

Flying
Whenever this creature enters or deals combat damage to a player, exile up to one target nonland permanent. For as long as that card remains exiled, its owner may cast it.
Whenever another player casts a spell from anywhere other than their hand, draw a card.

Azorius Chancery

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Arctic Treeline

({T}: Add {G} or {W}.)
This land enters tapped.

Cloudchaser Eagle

Flying
When this creature enters, destroy target enchantment.

Augury Owl

Flying
When this creature enters, scry 3. (Look at the top three cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Aven Cloudchaser

Flying (This creature can't be blocked except by creatures with flying or reach.)
When this creature enters, destroy target enchantment.

Beacon Hawk

Flying
Whenever this creature deals combat damage to a player, you may untap target creature.
{W}: This creature gets +0/+1 until end of turn.

Birds of Paradise

Sol Ring

Shield of the Oversoul

Enchant creature
As long as enchanted creature is green, it gets +1/+1 and has indestructible. (Damage and effects that say "destroy" don't destroy it. If its toughness is 0 or less, it still dies.)
As long as enchanted creature is white, it gets +1/+1 and has flying.

Soulcatcher

Flying
Whenever a creature with flying dies, put a +1/+1 counter on this creature.

Choco, Seeker of Paradise

Whenever one or more Birds you control attack, look at that many cards from the top of your library. You may put one of them into your hand. Then put any number of land cards from among them onto the battlefield tapped and the rest into your graveyard.
Landfall — Whenever a land you control enters, Choco gets +1/+0 until end of turn.

Flood Plain

This land enters tapped.
{T}, Sacrifice this land: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Migratory Route

Create four 1/1 white Bird creature tokens with flying.
Basic landcycling {2} ({2}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Arcane Signet

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

Sawtooth Loon

Flying
When this creature enters, return a white or blue creature you control to its owner's hand.
When this creature enters, draw two cards, then put two cards from your hand on the bottom of your library.

Seaside Citadel

This land enters tapped.
{T}: Add {G}, {W}, or {U}.

Command Tower

Alchemist's Refuge

{T}: Add {C}.
{G}{U}, {T}: You may cast spells this turn as though they had flash.

Wooded Bastion

{T}: Add {C}.
{G/W}, {T}: Add {G}{G}, {G}{W}, or {W}{W}.

Seaside Haven

{T}: Add {C}.
{W}{U}, {T}, Sacrifice a Bird: Draw a card.

Keeper of the Nine Gales

Flying
{T}, Tap two untapped Birds you control: Return target permanent to its owner's hand.

Island

Kastral, the Windcrested

Flying
Whenever one or more Birds you control deal combat damage to a player, choose one —
• You may put a Bird creature card from your hand or graveyard onto the battlefield with a finality counter on it.
• Put a +1/+1 counter on each Bird you control.
• Draw a card.

Watcher of the Spheres

Flying
Creature spells with flying you cast cost {1} less to cast.
Whenever another creature you control with flying enters, this creature gets +1/+1 until end of turn.

Warden of Evos Isle

Flying
Creature spells with flying you cast cost {1} less to cast.

Judge's Familiar

Flying
Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {1}.

Skycloud Expanse

Yavimaya Coast

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

Kangee, Aerie Keeper

Kicker {X}{2} (You may pay an additional {X}{2} as you cast this spell.)
Flying
When Kangee enters, if it was kicked, put X feather counters on it.
Other Bird creatures get +1/+1 for each feather counter on Kangee.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Dovescape

({W/U} can be paid with either {W} or {U}.)
Whenever a player casts a noncreature spell, counter that spell. That player creates X 1/1 white and blue Bird creature tokens with flying, where X is the spell's mana value.

Crookclaw Elder

Flying
Tap two untapped Birds you control: Draw a card.
Tap two untapped Wizards you control: Target creature gains flying until end of turn.

Evolving Wilds

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

Battle Screech

Create two 1/1 white Bird creature tokens with flying.
Flashback—Tap three untapped white creatures you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Icefeather Aven

Flying
Morph {1}{G}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When this creature is turned face up, you may return another target creature to its owner's hand.

Kangee, Sky Warden

Flying, vigilance
Whenever Kangee 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.

Azorius Keyrune

{T}: Add {W} or {U}.
{W}{U}: This artifact becomes a 2/2 white and blue Bird artifact creature with flying until end of turn.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Plains

Soulcatchers' Aerie

Whenever a Bird is put into your graveyard from the battlefield, put a feather counter on this enchantment.
Bird creatures get +1/+1 for each feather counter on this enchantment.

Empyrean Eagle

Flying
Other creatures you control with flying get +1/+1.

Noble Hierarch

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {G}, {W}, or {U}.

Terramorphic Expanse

Courier Hawk

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Emeria Angel

Flying
Landfall — Whenever a land you control enters, you may create a 1/1 white Bird creature token with flying.

Mist Raven

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

Seller of Songbirds

When this creature enters, create a 1/1 white Bird creature token with flying.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

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.

Flurry of Wings

Create X 1/1 white Bird Soldier creature tokens with flying, where X is the number of attacking creatures.

Sungrass Prairie

Treva's Ruins

When this land enters, sacrifice it unless you return a non-Lair land you control to its owner's hand.
{T}: Add {G}, {W}, or {U}.

Prairie Stream

({T}: Add {W} or {U}.)
This land enters tapped unless you control two or more basic lands.

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Grasslands

This land enters tapped.
{T}, Sacrifice this land: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

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.)

Muddle the Mixture

Counter target instant or sorcery spell.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Simic Growth Chamber

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Carrier Pigeons

Flying
When this creature enters, draw a card at the beginning of the next turn's upkeep.

Teshar, Ancestor's Apostle

Flying
Whenever you cast a historic spell, return target creature card with mana value 3 or less from your graveyard to the battlefield. (Artifacts, legendaries, and Sagas are historic.)