u/StormCloud-s

Okay so I'm running a DND campaign and this one character is meant to be a like millennium+ years old spellcaster who is, in the most literal way, connected and fused with the stars. I want to make them very powerful while keeping the cosmic elements, level and homebrew are completely on the table but race wise I haven't decided yet so I'd prefer if it wasn't super definitive for the build to work.

We're playing in DND 5e, could someone please help or offer advice/inspiration?