
Valafar The Black |

I have this player who is playing a part umbral dragon, spider, daemon, construct who worships Urgothoa and is her child. He is now a lich and a cult where his followers sacrifice powerful souls to his phylactery of the void so the player can gain power. He wants to become a god so he can take power from the rest of the gods and ruling everything.
I want this to happen, but what should I do

Valafar The Black |

His backstory is that he is the son of urgathoa, asmodeus, and all of the 4 horsemen. Since they could not have a child they made him out of highly advanced construct parts, a daemonic spider prince. They also took part of their souls and the soul of a great dragon to make him in hopes of controlling him. He was born from a great king. the pc killed the king and rose to power and created a cult saying that it will grant its followers ultimate power. The pc turn them all into liches and made them into one phylactery making it into his own hoping to gain power to overthrow his god parents. He has the power to steal souls into his great phylactery and control the souls within it

GM Rednal |
The Starstone is a traditional method. Alternately, they could gather "fragments of divinity" from around the multiverse, and putting them together elevates them up the ranks.
3.5 had a lot of stuff on becoming a deity that you can draw on.