Airdrop Aeronauts

Flying
Revolt — When Airdrop Aeronauts enters the battlefield, if a permanent you controlled left the battlefield this turn, you gain 5 life.

Accomplished Automaton

Fabricate 1 (When this creature enters the battlefield, put a +1/+1 counter on it or create a 1/1 colorless Servo artifact creature token.)

Lagrella, the Magpie

When Lagrella, the Magpie enters the battlefield, exile any number of other target creatures controlled by different players until Lagrella leaves the battlefield. When an exiled card enters the battlefield under your control this way, put two +1/+1 counters on it.

Adaptive Automaton

As Adaptive Automaton enters the battlefield, choose a creature type.
Adaptive Automaton is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Abominable Treefolk

Trample
Abominable Treefolk's power and toughness are each equal to the number of snow permanents you control.
When Abominable Treefolk enters the battlefield, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Amareth, the Lustrous

Flying
Whenever another permanent enters the battlefield under your control, look at the top card of your library. If it shares a card type with that permanent, you may reveal that card and put it into your hand.

Agent of Treachery

When Agent of Treachery enters the battlefield, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Angel of Invention

Flying, vigilance, lifelink
Fabricate 2 (When this creature enters the battlefield, put two +1/+1 counters on it or create two 1/1 colorless Servo artifact creature tokens.)
Other creatures you control get +1/+1.

Angelic Chorus

Whenever a creature enters the battlefield under your control, you gain life equal to its toughness.

Aerial Extortionist

Flying
Whenever Aerial Extortionist enters the battlefield or deals combat damage to a player, exile up to one target nonland permanent. For as long as that card remains exiled, its owner may cast it.
Whenever another player casts a spell from anywhere other than their hand, draw a card.

Academy Journeymage

This spell costs {1} less to cast if you control a Wizard.
When Academy Journeymage enters the battlefield, return target creature an opponent controls to its owner's hand.

Ampryn Tactician

When Ampryn Tactician enters the battlefield, creatures you control get +1/+1 until end of turn.

Alharu, Solemn Ritualist

When Alharu, Solemn Ritualist enters the battlefield, put a +1/+1 counter on each of up to two other target creatures.
Whenever a nontoken creature you control with a +1/+1 counter on it dies, create a 1/1 white Spirit creature token with flying.
Partner (You can have two commanders if both have partner.)

Altar of the Brood

Whenever another permanent enters the battlefield under your control, each opponent mills a card.

Acidic Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When Acidic Slime enters the battlefield, destroy target artifact, enchantment, or land.