what's something powerful you think a Rogue of Space could do? I see them taking the gravity from a star and adding it to themself, causing everything to be pulled at them at ridiculous speeds and being like a sort of mini solar system

I mean if you want them to be crushed under their own Gravitational Pull that sounds like a good idea. :^)

In all seriousness though, the coolest I can imagine would be taking the powers of a First Guardian, since they seem to be Space-Coded.