So, this is a Compendium Class I whipped up really quickly for a campaign that’s currently on hiatus. The players encountered a magical item which housed an arcane construct called an “Astral Guardian”. (In the game, Astral Guardians take names/inspiration from constellations. Star Pulses are their evil equivalent, being eldritch entities in the service of the cultists of the Elder Gods.)
It’s very heavily-inspired by JoJo’s Bizarre Adventure: Stardust Crusaders; Astral Guardians and Star Pulses are invisible to normal people, but their wielders can see them. They give special powers and abilities to their user.