Spoiler (click to reveal)
It says in 1689-4 to remove two villager cards in the Role card deck with the Sentinel and Cerberus. Then replace any remaining werewolf cards with villager cards. For 15 players, this is 4 werewolves. However, there seems to be only one spare villager card, excluding the two I have just removed. This means I am still lacking one villager card.