Agent of Kotis

Renew — {3}{U}, Exile this card from your graveyard: Put two +1/+1 counters on target creature. Activate only as a sorcery.

Aegis Sculptor

Flying
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
At the beginning of your upkeep, you may exile two cards from your graveyard. If you do, put a +1/+1 counter on this creature.

Arixmethes, Slumbering Isle

Arixmethes enters tapped with five slumber counters on it.
As long as Arixmethes has a slumber counter on it, it's a land. (It's not a creature.)
Whenever you cast a spell, you may remove a slumber counter from Arixmethes.
{T}: Add {G}{U}.

Academy Drake

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Flying
If this creature was kicked, it enters with two +1/+1 counters on it.

Adaptive Shimmerer

Flash
This creature enters with three +1/+1 counters on it.

Afterburner Expert

Exhaust — {2}{G}{G}: Put two +1/+1 counters on this creature. (Activate each exhaust ability only once.)
Whenever you activate an exhaust ability, return this card from your graveyard to the battlefield.

Aberrant

Ravenous (This creature enters with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Trample
Heavy Power Hammer — Whenever this creature deals combat damage to a player, destroy target artifact or enchantment that player controls.

Afiya Grove

This enchantment enters with three +1/+1 counters on it.
At the beginning of your upkeep, move a +1/+1 counter from this enchantment onto target creature.
When this enchantment has no +1/+1 counters on it, sacrifice it.

Aboleth Spawn

Flash
Ward {2}
Probing Telepathy — Whenever a creature entering under an opponent's control causes a triggered ability of that creature to trigger, you may copy that ability. You may choose new targets for the copy.