Andr, the Angel of the Nebula, is one of the four Angel sisters who serve Binary, the Lady of Shadow.
She and her sisters work to keep the Celestial Powers at bay, and keep the universe in balance so that Cthulhu never awakes again. They have dealt with the Moon Lord, Cthulhu's brother, multiple times when he attempted to upset their hard won balance.
Andr is the Maiden of Magic, and most of her abilities reflect calling upon the powers of nature to harm her foes, heal, protect, and even summon objectiles, (although the summoning charachteristic all sisters share, to an extent.) She has an insane personality- It is never known why her thoughts take their path.