Aven Riftwatcher

Flying
Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Aven Riftwatcher enters or leaves the battlefield, you gain 2 life.

Aether Adept

When Aether Adept enters, return target creature to its owner's hand.

Aven Eternal

Flying
When Aven Eternal enters, amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Automatic Librarian

When Automatic Librarian enters, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Aven Surveyor

Flying
When Aven Surveyor enters, choose one —
• Put a +1/+1 counter on Aven Surveyor.
• Return target creature to its owner's hand.

Azorius Arrester

When Azorius Arrester enters, detain target creature an opponent controls. (Until your next turn, that creature can't attack or block and its activated abilities can't be activated.)

Augury Owl

Flying
When Augury Owl enters, scry 3. (Look at the top three cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Soulherder

Whenever a creature is exiled from the battlefield, put a +1/+1 counter on Soulherder.
At the beginning of your end step, you may exile another target creature you control, then return that card to the battlefield under its owner's control.

Apothecary Geist

Flying
When Apothecary Geist enters, if you control another Spirit, you gain 3 life.

Basilica Shepherd

Flying
When Basilica Shepherd enters, create two 1/1 colorless Phyrexian Mite artifact creature tokens with toxic 1 and "This creature can't block." (Players dealt combat damage by them also get a poison counter.)