Halimar Excavator

Whenever Halimar Excavator or another Ally enters the battlefield under your control, target player mills X cards, where X is the number of Allies you control.

Plains

Ondu Cleric

Whenever Ondu Cleric or another Ally enters the battlefield under your control, you may gain life equal to the number of Allies you control.

Kabira Evangel

Whenever Kabira Evangel or another Ally enters the battlefield under your control, you may choose a color. If you do, Allies you control gain protection from the chosen color until end of turn.

Island

Jwari Shapeshifter

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

Glacial Fortress

Glacial Fortress enters the battlefield tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Reflections of Littjara

As Reflections of Littjara enters the battlefield, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Aether Vial

At the beginning of your upkeep, you may put a charge counter on Aether Vial.
{T}: You may put a creature card with mana value equal to the number of charge counters on Aether Vial from your hand onto the battlefield.

Panharmonicon

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

Kazandu Blademaster

First strike, vigilance
Whenever Kazandu Blademaster or another Ally enters the battlefield under your control, you may put a +1/+1 counter on Kazandu Blademaster.

Sea Gate Loremaster

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

Herald's Horn

As Herald's Horn enters the battlefield, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Ancient Ziggurat

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

Ally Encampment

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast an Ally spell.
{1}, {T}, Sacrifice Ally Encampment: Return target Ally you control to its owner's hand.

Gideon, Ally of Zendikar

+1: Until end of turn, Gideon, Ally of Zendikar becomes a 5/5 Human Soldier Ally creature with indestructible that's still a planeswalker. Prevent all damage that would be dealt to him this turn.
0: Create a 2/2 white Knight Ally creature token.
−4: You get an emblem with "Creatures you control get +1/+1."

Umara Raptor

Flying
Whenever Umara Raptor or another Ally enters the battlefield under your control, you may put a +1/+1 counter on Umara Raptor.