And there you have it: "to become God" is Deum fieri.
What does Deus Fio mean?
Famous last words of Emperor Vespasian "Vae, puto deus fio"~"I think I'm becoming a god" reflects that emperors became gods upon their death.
What origin is Deus?
Deus (Classical Latin: [ˈd̪e. ʊs], Ecclesiastical Latin: [ˈd̪ɛː. us]) is the Latin word for "god" or "deity". Latin deus and dīvus ("divine") are in turn descended from Proto-Indo-European *deiwos, "celestial" or "shining", from the same root as *Dyēus, the reconstructed chief god of the Proto-Indo-European pantheon.