Ok, this one has a bit of a... different end game, should it come to Final Battle.
http://boardgamegeek.com/file/info/38091
Mnomquah would be the GOO obviously, the scenario, monster token and map are all for the Final Battle, as described on his sheet. In short, when he wakes up you put the Horror of the Black Lake scenario in play and move all investigators to the Lake of Ubboth map, placing the Mnomquah monster token in the center (The map is currently having issues, probably because I forgot to upload each location file. The update is currently pending and should be up in a day or so). Gates open up on the outskirts of the map and spew out monsters, which the investigators must battle and close. Meanwhile, Mnomquah's token moves (As a fast stalker) after them and starts kicking tail. Basically, combat with him is started like a normal monster, but you use the statistics on his AO sheet just like a normal final battle (You may still flee, though). The end result is that the endgame is slightly more dynamic, but I'm unsure whether it's harder or easier.