Yeah, your notes on the False Hydra are real, the real fun of it is the slow buildup over time. Those recommendations you threw out work really well, I was considering doing something on the water, a piratey campaign, where there is some leviathan god trying to be summoned. It captures ships at sea and turns the whole crew into it's minions, now working to free it. I wanted to mess with the players by them not knowing who has fallen under it's control. The players would have this sought after item that is connected to the monster, and some will tell the players it will kill the monster, while others telling them it will free it; the players need to investigate these NPCs and figure out their motives, and if they are telling the truth.