@RefurioAnachro Hi, I found it by searching "gnostic diagram" on Google Image Search. Several similar diagrams turned up with the title "Ophite Diagram", but this particular diagram was from "The Diagram of the Ophites: a Synthesis", Australian Religion Studies Review 1997, as scraped by:

https://www.semanticscholar.org/paper/The-Diagram-of-the-Ophites%3A-a-Synthesis-Vassallo/4d8dc548628b0c98d0c62c08564e1b444e074333