what powers does the crystal poses.

All I know is that it restored Xavier's powers and is where the White Hot Room is located.

It can suck in the universe into a demension populated only by neutron stars. That's where it's power comes from. So neutronium is plentiful there. It is highly unlikely that the crystal itself is made of Neutronium if it was a crystal that big would be impossible to be carried by most ships But if fully tapped it could destroy the universe due to the gravity. I wonder why the living tribunal hasn't paid much attention to it. Because if one, just one strange matter atom gets into that universe it would be a disaster as every neutron star would be converted into strange matter. And that would increase the gravity further causing massive instability Possibly even a big crunch and if that happens then I bet the crystal will be rendered useless or implode

Powerful enough to beat Galactus with a few other objects.

It also "killed" Sunspot at the Age of Apocalypse timeline... So much energy to absorb that could not be contained. poor Sunspot...