Angelic Arbiter

Flying
Each opponent who cast a spell this turn can't attack with creatures.
Each opponent who attacked with a creature this turn can't cast spells.

Aerie Mystics

Flying
{1}{G}{U}: Creatures you control gain shroud until end of turn. (They can't be the targets of spells or abilities.)

Adarkar Valkyrie

Flying, vigilance
{T}: When target creature other than Adarkar Valkyrie dies this turn, return that card to the battlefield under your control.

Ancestor Dragon

Flying
Whenever one or more creatures you control attack, you gain 1 life for each attacking creature.

Angelic Field Marshal

Flying
Lieutenant — As long as you control your commander, Angelic Field Marshal gets +2/+2 and creatures you control have vigilance.

Derevi, Empyrial Tactician

Flying
Whenever Derevi, Empyrial Tactician enters the battlefield or a creature you control deals combat damage to a player, you may tap or untap target permanent.
{1}{G}{W}{U}: Put Derevi onto the battlefield from the command zone.

Angel of Destiny

Flying, double strike
Whenever a creature you control deals combat damage to a player, you and that player each gain that much life.
At the beginning of your end step, if you have at least 15 life more than your starting life total, each player Angel of Destiny attacked this turn loses the game.

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.

Angelic Guardian

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever one or more creatures you control attack, they gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Akroma, Vision of Ixidor

Flying, first strike, vigilance, trample
At the beginning of each combat, until end of turn, each other creature you control gets +1/+1 if it has flying, +1/+1 if it has first strike, and so on for double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, protection, reach, trample, vigilance, and partner.
Partner