Child of Alara

Trample
When Child of Alara dies, destroy all nonland permanents. They can't be regenerated.

Academy Rector

When Academy Rector dies, you may exile it. If you do, search your library for an enchantment card, put that card onto the battlefield, then shuffle.

Anje, Maid of Dishonor

Whenever Anje, Maid of Dishonor and/or one or more other Vampires you control enter, create a Blood token. This ability triggers only once each turn. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
{2}, Sacrifice another creature or a Blood token: Each opponent loses 2 life and you gain 2 life.

Arasta of the Endless Web

Reach
Whenever an opponent casts an instant or sorcery spell, create a 1/2 green Spider creature token with reach.

Anthousa, Setessan Hero

Heroic — Whenever you cast a spell that targets Anthousa, Setessan Hero, up to three target lands you control each become 2/2 Warrior creatures until end of turn. They're still lands.

Abbey Matron

{W}, {T}: Abbey Matron gets +0/+3 until end of turn.

Akroma, Angel of Wrath

Flying, first strike, vigilance, trample, haste, protection from black and from red

Agent of Masks

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