Conversation so far:
What was his relationship with Cosmology?
There is no one single authoritative account of the creation of the cosmos, but rather a series of several accounts.
What were some of the accounts?
In these texts, instead of a large pleroma, there is a discrete division between light and darkness.
What divides them?
The ruler of darkness is called Ptahil (similar to the Gnostic Demiurge), and the originator of the light.

Question: Can you elaborate on this?
Self-contained rewrite: Can you elaborate on  Mandaeism accounts of the creation?