Leave Blue Star, ascend to godhood in space.
Leaving Blue Star isn't difficult. Legends are perfectly capable of breaking through the atmosphere and surviving in space for short periods.
As long as they don't stray too far from Blue Star and remain in its vicinity, there's basically no danger.
The difficult part is still ascending to godhood.
If one hopes to ascend to godhood by absorbing a Tier 7 extract, the Nian Race's Tier 7 extracts are not so easy to come by.
By the time they're willing to give Su Ze a Tier 7 extract, they will have undoubtedly made various preparations to prevent him from slipping away.
They might hand him the extract one moment, only to contact the Nian Race's Mother Star the next to send people over.
