Halimar Tidecaller

When this creature enters, you may return target card with awaken from your graveyard to your hand.
Land creatures you control have flying.

Lantern Scout

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

Oran-Rief Survivalist

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

Skyrider Elf

Flying
Converge — This creature enters with a +1/+1 counter on it for each color of mana spent to cast it.

Tajuru Warcaller

Rally — Whenever this creature or another Ally you control enters, creatures you control get +2/+2 until end of turn.

Talus Paladin

Whenever this creature or another Ally you control enters, you may have Allies you control gain lifelink until end of turn, and you may put a +1/+1 counter on this creature.

Momo, Friendly Flier

Flying
The first non-Lemur creature spell with flying you cast during each of your turns costs {1} less to cast.
Whenever another creature you control with flying enters, Momo gets +1/+1 until end of turn.

Munda's Vanguard

Cohort — {T}, Tap an untapped Ally you control: Put a +1/+1 counter on each creature you control.

Stoneforge Acolyte

Cohort — {T}, Tap an untapped Ally you control: Look at the top four cards of your library. You may reveal an Equipment card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Hero of Goma Fada

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

Halimar Excavator

Whenever this creature or another Ally you control enters, target player mills X cards, where X is the number of Allies you control.

Jwari Shapeshifter

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

Tajuru Stalwart

Converge — This creature enters with a +1/+1 counter on it for each color of mana spent to cast it.

Ondu Cleric

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

Stone Haven Outfitter

Equipped creatures you control get +1/+1.
Whenever an equipped creature you control dies, draw a card.

Kabira Evangel

Whenever this creature or another Ally you control enters, you may choose a color. If you do, Allies you control gain protection from the chosen color until end of turn.

Joraga Bard

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

Katara, the Fearless

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

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.

Harabaz Druid

{T}: Add X mana of any one color, where X is the number of Allies you control.

Umara Raptor

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

Hada Freeblade

Makindi Patrol

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

Kazandu Blademaster

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

Veteran Warleader

Veteran Warleader's power and toughness are each equal to the number of creatures you control.
Tap another untapped Ally you control: This creature gains your choice of first strike, vigilance, or trample until end of turn.

Turntimber Ranger

Whenever this creature or another Ally you control enters, you may create a 2/2 green Wolf creature token. If you do, put a +1/+1 counter on this creature.

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.

Katara, Water Tribe's Hope

Vigilance
When Katara enters, create a 1/1 white Ally creature token.
Waterbend {X}: Creatures you control have base power and toughness X/X until end of turn. X can't be 0. Activate only during your turn. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

Avatar Enthusiasts

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

Sea Gate Loremaster

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

Beastcaller Savant

Haste
{T}: Add one mana of any color. Spend this mana only to cast a creature spell.

Tajuru Archer

Whenever this creature or another Ally you control enters, you may have this creature deal damage to target creature with flying equal to the number of Allies you control.

Kor Bladewhirl

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