What was the "Hydra" that is coupled with Dagon that rules the Deep Ones then? I believe we saw it in the 1990's cartoon "Big Guy & Rusty the Boy Robot" in the episode near an abyss is a monstrous tentacled creature that is intelligent and creates fake duplicates of people. Fortunately it is sent back into the abyss and then closed to save Earth for a time anyway.
Idk if you're familiar, but DandD has what is called a "false Hydra" that fits a similar description. Also, I always thought that Mother Hydra, while given that name, was not a hydra per se. Idk. Just a thought.
You are doing the Lord Azathoth’s work. These stories make my long hours of driving go by a little faster. May the Elder Sign protect you fellow cultist.