It says it right in the description of "Summon Aery", I also assume you mean Zilean's E (the speed boost / slow)
PASSIVE: **Damaging **an enemy champion signals Aery to dash to them, dealing 10 − 40 (based on level) (+ 15% bonus AD) (+ 10% AP) Attack damageAbility power Adaptive damage.
Zilean's E doesn't do damage.
Healing, shielding or **buffing ** an ally signals Aery to dash to them, shielding them for 35 − 80 (based on level) (+ 40% bonus AD) (+ 25% AP) for 2 seconds.
Zilean's E is classified as a buff which is why it applies Aery.
Not really misleading at all.