Third of my Herald designs for my Elder Sign: Abominations project.
As such, it isn't really a Herald in the usual sense of the word, more of a rule sheets to define a new End Game / Winning Condition. Now to win you need to collect the required number of Elder Signs and defeat the Ancient One.
I would strongly recommend this Herald is considered even if you do not use any of the other Elder Sign: Abomination components.
The Great Old Ones Herald sheet
Note that now collecting Elder Sign rewards (page 8 of the rules) are optional. While most of the time you would always collect the Elder Sign, there are certain situations where you most definitely do not want to collect the final Elder Sign and awaken the Ancient One.
In particular, Yig
When Yig awakens, each investigator must return a Common Item, Unique Item, and Spell or be devoured.
You might now want to delay awakening the AO before your Investigators have the required Items (assuming you have time before the final Doom token is placed).
There are also a bunch of AO attacks that are in the form of "When AO attacks, each investigator must discard xxx or be devoured. Players may want to delay the AO from awakening in certain circumstances.
There are some situations (typically when using Bokrug or Shudde M'ell as the Herald) where you are required to add Doom tokens at the start of the final battle. If required to do this then the number of Doom tokens can exceed the number of spaces on the Doom track.
The following is some personal comment.
I find the game much more interesting now that you need to defeat the Ancient One in the final battle. While this new rule does add length to the game, it adds a dramatic conclusion to the game. To some extent it also stops players from being able to game the system and just build up for the final battle. Plus, what's the point of having a final boss is you don't even need to defeat him to win?
For those who think that it isn't thematic that you should be able to win against an Ancient One, I agree. My viewpoint is that you never actually kill the Ancient One anyway, even if you defeat him, all you do is return him to his slumber. There he dreams biding his time before he extracts his revenge on an unsuspecting world.
I will add this Herald to my Elder Sign: Abominations - Game Expansion project files soon.
The above image in LQ (150dpi), the download will be in 300dpi. If you have any comments or spot any errors then please let me know. And yes, this is a direct copy of my BGG thread :)