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.

Great Divide Guide

Each land and Ally you control has "{T}: Add one mana of any color."

Seascape Aerialist

Whenever this creature or another Ally you control enters, you may have Ally creatures you control gain flying until end of turn.

Haru, Hidden Talent

Whenever another Ally you control enters, earthbend 1. (Target land you control becomes a 0/0 creature with haste that's still a land. Put a +1/+1 counter on it. When it dies or is exiled, return it to the battlefield tapped.)

Aang, Airbending Master

When Aang enters, airbend another target creature. (Exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)
Whenever one or more creatures you control leave the battlefield without dying, you get an experience counter.
At the beginning of your upkeep, create a 1/1 white Ally creature token for each experience counter you have.

Hada Freeblade

Whenever this creature or another Ally you control enters, you may put a +1/+1 counter on this creature.

South Pole Voyager

Whenever this creature or another Ally you control enters, you gain 1 life. If this is the second time this ability has resolved this turn, draw a card.

Makindi Patrol

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

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.

Sea Gate Loremaster

{T}: Draw a card for each Ally you control.

Jwari Shapeshifter

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

White Lotus Reinforcements

Vigilance
Other Allies you control get +1/+1.

Ondu Cleric

Whenever this creature or another Ally you control enters, you may gain life equal to the number of Allies you control.

Lantern Scout

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

Appa, Steadfast Guardian

Flash
Flying
When Appa enters, airbend any number of other target nonland permanents you control. (Exile them. While each one is exiled, its owner may cast it for {2} rather than its mana cost.)
Whenever you cast a spell from exile, create a 1/1 white Ally creature token.

The Earth King

When The Earth King enters, create a 4/4 green Bear creature token.
Whenever one or more creatures you control with power 4 or greater attack, search your library for up to that many basic land cards, put them onto the battlefield tapped, then shuffle.

Katara, the Fearless

If a triggered ability of an Ally you control triggers, that ability triggers an additional time.

Realmwalker

Changeling (This card is every creature type.)
As this creature enters, choose a creature type.
You may look at the top card of your library any time.
You may cast creature spells of the chosen type from the top of your library.

Hero of Goma Fada

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

Suki, Kyoshi Warrior

Suki's power is equal to the number of creatures you control.
Whenever Suki attacks, create a 1/1 white Ally creature token that's tapped and attacking.

Earth Kingdom Jailer

When this creature enters, exile up to one target artifact, creature, or enchantment an opponent controls with mana value 3 or greater until this creature leaves the battlefield.

Sokka's Charge

During your turn, Allies you control have double strike and lifelink.

Aang and La, Ocean's Fury

Reach, trample
Whenever Aang and La attack, put a +1/+1 counter on each tapped creature you control.

Aang, Swift Savior

Flash
Flying
When Aang enters, airbend up to one other target creature or spell. (Exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)
Waterbend {8}: Transform Aang.

Aang, Swift Savior // Aang and La, Ocean's Fury

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Kindred Discovery

As this enchantment enters, choose a creature type.
Whenever a creature you control of the chosen type enters or attacks, draw a card.

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

Aang, Destined Savior

Flying
Land creatures you control have vigilance.
At the beginning of combat on your turn, earthbend 2. (Target land you control becomes a 0/0 creature with haste that's still a land. Put two +1/+1 counters on it. When it dies or is exiled, return it to the battlefield tapped.)

Aang, at the Crossroads

Flying
When Aang enters, look at the top five cards of your library. You may put a creature card with mana value 4 or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
When another creature you control leaves the battlefield, transform Aang at the beginning of the next upkeep.

Aang, at the Crossroads // Aang, Destined Savior

Swords to Plowshares

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

Hakoda, Selfless Commander

Vigilance
You may look at the top card of your library any time.
You may cast Ally spells from the top of your library.
Sacrifice Hakoda: Creatures you control get +0/+5 and gain indestructible until end of turn.