New Ancient City mob

Imagine this: a mob simular to a vex or allay, but not bright blue. Skulk-wings, dark green and black colors, glowing turquoise slits for eyes. This creature hides within the larger structures of the ancient city, and is silent in flight. This silence would be a great pair with the Warden itself. If a Hoard sees you, its wings will light up before charging. The Hoard will guard chests of higher value, but only one per valuable chest. The creature fears the sight of echo shards, and will hide from its owner. It drops nothing but a skulk block and experience, and is wise to avoid. Just a thought, but it might be a cool addition to vanilla...