Adipose Offspring

Emerge {5}{W} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.)
When this creature enters, create a 2/2 white Alien creature token. If this creature's emerge cost was paid, instead create X of those tokens, where X is the sacrificed creature's toughness.

Wild Pair

Whenever a creature enters, if you cast it from your hand, you may search your library for a creature card with the same total power and toughness, put it onto the battlefield, then shuffle.

Mentor of the Meek

Whenever another creature you control with power 2 or less enters, you may pay {1}. If you do, draw a card.

Arcus Acolyte

Reach, lifelink
Outlast {G/W} ({G/W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each other creature you control without a +1/+1 counter on it has outlast {G/W}.

Alpine Houndmaster

When this creature enters, you may search your library for a card named Alpine Watchdog and/or a card named Igneous Cur, reveal them, put them into your hand, then shuffle.
Whenever this creature attacks, it gets +X/+0 until end of turn, where X is the number of other attacking creatures.

Duskana, the Rage Mother

When Duskana enters, draw a card for each creature you control with base power and toughness 2/2.
Whenever a creature you control with base power and toughness 2/2 attacks, it gets +3/+3 until end of turn.

Arashin Foremost

Double strike
Whenever this creature enters or attacks, another target Warrior creature you control gains double strike until end of turn.

Acolyte Hybrid

Heavy Rock Cutter — Whenever this creature attacks, destroy up to one target artifact. If an artifact is destroyed this way, its controller draws a card.

Anger

Haste
As long as this card is in your graveyard and you control a Mountain, creatures you control have haste.

Assemble the Players

You may look at the top card of your library any time.
Once each turn, you may cast a creature spell with power 2 or less from the top of your library.

Felidar Retreat

Landfall — Whenever a land you control enters, choose one —
• Create a 2/2 white Cat Beast creature token.
• Put a +1/+1 counter on each creature you control. Those creatures gain vigilance until end of turn.

Blessed Sanctuary

Prevent all noncombat damage that would be dealt to you and creatures you control.
Whenever a nontoken creature you control enters, create a 2/2 white Unicorn creature token.

Agitator Ant

At the beginning of your end step, each player may put two +1/+1 counters on a creature they control. Goad each creature that had counters put on it this way. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Ayula, Queen Among Bears

Whenever another Bear you control enters, choose one —
• Put two +1/+1 counters on target Bear.
• Target Bear you control fights target creature you don't control.

Alpine Watchdog

Vigilance (Attacking doesn't cause this creature to tap.)

Atalan Jackal

Trample, haste
Skilled Outrider — Whenever this creature deals combat damage to a player, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.