Angelic Chorus

Whenever a creature you control enters, you gain life equal to its toughness.

Aether Channeler

When Aether Channeler enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.

Amareth, the Lustrous

Flying
Whenever another permanent you control enters, 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.

Spirited Companion

When Spirited Companion enters, draw a card.

Abundant Growth

Enchant land
When Abundant Growth enters, draw a card.
Enchanted land has "{T}: Add one mana of any color."

Seasoned Cathar

Ambitious Farmhand

When Ambitious Farmhand enters, you may search your library for a basic Plains card, reveal it, put it into your hand, then shuffle.
Coven — {1}{W}{W}: Transform Ambitious Farmhand. Activate only if you control three or more creatures with different powers.

Ambitious Farmhand // Seasoned Cathar

Ajani's Welcome

Whenever a creature you control enters, you gain 1 life.

Aesi, Tyrant of Gyre Strait

You may play an additional land on each of your turns.
Landfall — Whenever a land you control enters, you may draw a card.

Alchemist's Vial

When Alchemist's Vial enters, draw a card.
{1}, {T}, Sacrifice Alchemist's Vial: Target creature can't attack or block this turn.

Elesh Norn, Mother of Machines

Vigilance
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Permanents entering don't cause abilities of permanents your opponents control to trigger.