Highland Berserker

Whenever Highland Berserker or another Ally enters the battlefield under your control, you may have Ally creatures you control gain first strike until end of turn.

Oran-Rief Survivalist

Whenever Oran-Rief Survivalist or another Ally enters the battlefield under your control, you may put a +1/+1 counter on Oran-Rief Survivalist.

Mountain

Evolving Wilds

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

Harabaz Druid

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

Vastwood Animist

{T}: Target land you control becomes an X/X Elemental creature until end of turn, where X is the number of Allies you control. It's still a land.

Flame Slash

Flame Slash deals 4 damage to target creature.

Akoum Battlesinger

Haste
Whenever Akoum Battlesinger or another Ally enters the battlefield under your control, you may have Ally creatures you control get +1/+0 until end of turn.

Quest for the Gemblades

Whenever a creature you control deals combat damage to a creature, you may put a quest counter on Quest for the Gemblades.
Remove a quest counter from Quest for the Gemblades and sacrifice it: Put four +1/+1 counters on target creature.

Graypelt Hunter

Trample
Whenever Graypelt Hunter or another Ally enters the battlefield under your control, you may put a +1/+1 counter on Graypelt Hunter.

Stonework Puma

Tajuru Archer

Whenever Tajuru Archer or another Ally enters the battlefield under your control, you may have Tajuru Archer deal damage to target creature with flying equal to the number of Allies you control.

Forest

Kazuul Warlord

Whenever Kazuul Warlord or another Ally enters the battlefield under your control, you may put a +1/+1 counter on each Ally creature you control.