Aerial Responder

Anafenza, Kin-Tree Spirit

Whenever another nontoken creature you control enters, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Ballynock Cohort

First strike
Ballynock Cohort gets +1/+1 as long as you control another white creature.

Brimaz, King of Oreskos

Vigilance
Whenever Brimaz, King of Oreskos attacks, create a 1/1 white Cat Soldier creature token with vigilance that's attacking.
Whenever Brimaz blocks a creature, create a 1/1 white Cat Soldier creature token with vigilance that's blocking that creature.

Aerie Auxiliary

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