"In this corner, weighing in at a svelte 3,765 pounds, from Another Dimension, the King in Yellow - it's Hastur the Ancient One! And in this corner, weighing 118 pounds, from Arkham, Massachusetts, psychologist Carolyn Fern! It's a fight to the finish, and only one of them will come out alive!"
Oh, forget the hype. Carolyn wins, every time.
Why? Because Elder Sign dispenses with the idea of an Upkeep, referring instead to the "start of turn" without designating "Start of Turn" to be an official phase of a player's turn. That means Dr. Fern can heal herself one Sanity (assuming she isn't already maxed) at the beginning of each of her turns, before she does anything else on her turn. So even if she's the only investigator left once Hastur's awake, she has to win... eventually, as follows:
Midnight - Hastur attacks for 2 Sanity. Fern now heals herself for 1 Sanity and attacks. Maybe she removes a Doom token, maybe not. Sooner or later, she'll hit for the twelfth time and win the game for the investigators. End of turn, advance the Clock to 3:00. Fern gains 1 Sanity (she is now back to the same Sanity level as before Hastur's attack) and attacks, and advances the Clock to 6:00. Fern gains another Sanity (now irrelevant) and attacks, and advances the Clock to 9:00. Fern gains another Sanity and attacks, and advances the Clock to Midnight. Repeat until Hastur is dead Sure, Fern isn't 100% accurate, but when your opponent can't kill you, you don't have to be. Sooner or later, you will win.
I'm sure there are other examples of an investigator defeating a particular Ancient One in this same fashion, because of the lapse in the rules. Suggestion: Change Fern's and Lee's abilities to read "Once per day... ". We were a bit disappointed to invest two hours in a six-player game only to find this problem at the end. The game's great otherwise; please fix the rules? Thanks for taking the time to read this.