Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Atraxa's Fall

Destroy target artifact, battle, enchantment, or creature with flying.

Arboreal Grazer

Reach
When Arboreal Grazer enters, you may put a land card from your hand onto the battlefield tapped.

Augury Owl

Flying
When Augury Owl enters, scry 3. (Look at the top three cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Alchemist's Retrieval

Cleave {1}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Return target nonland permanent [you control] to its owner's hand.

Aven Fisher

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Aven Fisher dies, you may draw a card.

Aether Spike

Choose target spell. You get {E}{E} (two energy counters), then you may pay any amount of {E}. Counter that spell unless its controller pays {1} for each {E} paid this way.

Avenging Hunter

Trample
When Avenging Hunter enters, you take the initiative.

Ankle Biter

Bubble Up

Put target instant or sorcery card from your graveyard on top of your library. (Then exile this card. You may cast the creature later from exile.)

Aquatic Alchemist

Whenever you cast your first instant or sorcery spell each turn, Aquatic Alchemist gets +2/+0 until end of turn.

Aquatic Alchemist // Bubble Up

Tatyova, Benthic Druid

Landfall — Whenever a land you control enters, you gain 1 life and draw a card.