Agent of Masks

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

Plains

Acolyte of Affliction

When Acolyte of Affliction enters, mill two cards, then you may return a permanent card from your graveyard to your hand.

Abzan Falconer

Outlast {W} ({W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has flying.

Ahn-Crop Champion

You may exert Ahn-Crop Champion as it attacks. When you do, untap all other creatures you control. (An exerted creature won't untap during your next untap step.)

Golgari Guildgate

Golgari Guildgate enters tapped.
{T}: Add {B} or {G}.

Ambush Paratrooper

Flash
Flying
{5}: Creatures you control get +1/+1 until end of turn.

Alloy Animist

{2}{G}: Until end of turn, target noncreature artifact you control becomes a 4/4 artifact creature.

Aether Poisoner

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When Aether Poisoner enters, you get {E}{E} (two energy counters).
Whenever Aether Poisoner attacks, you may pay {E}{E}. If you do, create a 1/1 colorless Servo artifact creature token.

Anafenza, the Foremost

Whenever Anafenza, the Foremost attacks, put a +1/+1 counter on another target tapped creature you control.
If a nontoken creature an opponent owns would die or a creature card not on the battlefield would be put into an opponent's graveyard, exile that card instead.

Affa Protector

Godless Shrine

({T}: Add {W} or {B}.)
As Godless Shrine enters, you may pay 2 life. If you don't, it enters tapped.

Angelheart Protector

When Angelheart Protector enters, target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Agadeem Occultist

{T}: Put target creature card from an opponent's graveyard onto the battlefield under your control if its mana value is less than or equal to the number of Allies you control.

Acolyte of Xathrid

Forest

Sigarda, Heron's Grace

Flying
You and Humans you control have hexproof.
{2}, Exile a card from your graveyard: Create a 1/1 white Human Soldier creature token.

Sigarda, Champion of Light

Flying, trample
Humans you control get +1/+1.
Coven — Whenever Sigarda attacks, if you control three or more creatures with different powers, look at the top five cards of your library. You may reveal a Human creature card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Ancestor's Chosen

First strike (This creature deals combat damage before creatures without first strike.)
When Ancestor's Chosen enters, you gain 1 life for each card in your graveyard.

Swamp

Agatha's Champion

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Trample
When Agatha's Champion enters, if it was bargained, it fights up to one target creature you don't control. (Each deals damage equal to its power to the other.)

Anointed Chorister

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
{4}{W}: Anointed Chorister gets +3/+3 until end of turn.

Abzan Guide

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Morph {2}{W}{B}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)