Aerie Auxiliary

Flying
When Aerie Auxiliary enters, support 2. (Put a +1/+1 counter on each of up to two other target creatures.)

Absolver Thrull

Haunt (When this creature dies, exile it haunting target creature.)
When Absolver Thrull enters or the creature it haunts dies, destroy target enchantment.

Aether Adept

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

Teleportation Circle

At the beginning of your end step, exile up to one target artifact or creature you control, then return that card to the battlefield under its owner's control.

Niko, Light of Hope

When Niko, Light of Hope enters, create two Shard tokens. (They're enchantments with "{2}, Sacrifice this enchantment: Scry 1, then draw a card.")
{2}, {T}: Exile target nonlegendary creature you control. Shards you control become copies of it until the beginning of the next end step. Return it to the battlefield under its owner's control at the beginning of the next end step.

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.