Agent of Masks

At the beginning of your upkeep, each opponent loses 1 life. You gain life equal to the life lost this way.

Auratouched Mage

When this creature enters, search your library for an Aura card that could enchant it. If this creature is still on the battlefield, put that Aura card onto the battlefield attached to it. Otherwise, reveal the Aura card and put it into your hand. Then shuffle.

Aetherplasm

Whenever this creature blocks a creature, you may return this creature to its owner's hand. If you do, you may put a creature card from your hand onto the battlefield blocking that creature.

Aquastrand Spider

Graft 2 (This creature enters with two +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{G}: Target creature with a +1/+1 counter on it gains reach until end of turn. (It can block creatures with flying.)

Azorius Ploy

Prevent all combat damage target creature would deal this turn.
Prevent all combat damage that would be dealt to target creature this turn.

Azorius Aethermage

Whenever a permanent is returned to your hand, you may pay {1}. If you do, draw a card.