From what I know about the left hand path a lot of it comes from Kenneth Grant and his offshoots like the TOTO, and its successors like Dragon Rouge, OTO Antiqua (Gnostic Voudon), and Temple of Ascending Flame. All of these are Grantian groups.

Whereas the church of Satan, Temple of Set, etc are from a kind of different group. Typhon/Apophis is an adversary in Golden Dawn magic so it's a similar concept.