Appa, Loyal Sky Bison

Flying
Whenever Appa enters or attacks, choose one —
• Target creature you control gains flying until end of turn.
• Airbend another target nonland permanent you control. (Exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)

Aang, Air Nomad

Flying (This creature can't be blocked except by creatures with flying or reach.)
Vigilance (Attacking doesn't cause this creature to tap.)
Other creatures you control have vigilance.

Affa Protector

Glider Kids

Flying
When this creature enters, scry 1. (Look at the top card of your library. You may put it on the bottom.)

Water Tribe Captain

{5}: Creatures you control get +1/+1 until end of turn.

Jeong Jeong's Deserters

When this creature enters, put a +1/+1 counter on target creature.

Arcane Signet

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

Aang, the Last Airbender

Flying
When Aang enters, airbend up to one other target nonland permanent. (Exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)
Whenever you cast a Lesson spell, Aang gains lifelink until end of turn.

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.)

Kyoshi Warrior Guard

Appa, Aang's Companion

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever Appa attacks, another target attacking creature without flying gains flying until end of turn.

Momo, Playful Pet

Flying, vigilance
When Momo leaves the battlefield, choose one —
• Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
• Put a +1/+1 counter on target creature you control.
• Scry 2.

Sol Ring

Cliffside Lookout

{4}{W}: Creatures you control get +1/+1 until end of turn.

Hero of Goma Fada

Rally — Whenever this creature or another Ally you control enters, creatures you control gain indestructible until end of turn.

Expedition Envoy

Invasion Reinforcements

Flash
When this creature enters, create a 1/1 white Ally creature token.

Spawnbinder Mage

Cohort — {T}, Tap an untapped Ally you control: Tap target creature.

Inspired Insurgent

{1}, Sacrifice this creature: Destroy target artifact or enchantment.

Earth Kingdom Protectors

Vigilance
Sacrifice this creature: Another target Ally you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Compassionate Healer

Whenever this creature becomes tapped, you gain 1 life and scry 1. (Look at the top card of your library. You may put it on the bottom.)

Plains

Appa, the Vigilant

Flying, vigilance
Whenever Appa or another Ally you control enters, creatures you control get +1/+1 and gain flying and vigilance until end of turn.

Kyoshi Warriors

When this creature enters, create a 1/1 white Ally creature token.

Kor Sky Climber

{1}{W}: This creature gains flying until end of turn.

Angel of Renewal

Flying
When this creature enters, you gain 1 life for each creature you control.