1) Prepare a separate monster cup for all the masks.
2) Each time a monster surge occurs, draw a random mask and put it in play on the surging gate. If a generic monster surge occurs as a result of a specific Mythos card(that is, with no gate opening location), a mask would emerge from every open gate on the board.
3)Masks are spawn monsters; they don't count against the monster limit, and are not removed from the board when a gate with their dimensional symbol is closed or sealed.
4) Each time an investigator defeats a mask, return it to the masks' cup, unless he can ignore their Endless ability. Any masks that are claimed as monster trophies can be spent as Clue tokens for the purpose of sealing gates and in final battle against Nyarlothotep.
5) Each time a mask is evaded , put it on Nyarlothotep's sheet along with a Clue token from the bank.
6) For each mask on Nyarlothotep's sheet, the total amount of Clue tokens required to seal a gate is increased by 1.
7) Should Nyarlothotep awaken, all mask monsters on its sheet must be defeated before proceeding to final battle.
Getting a better weapon or spell to take her down just didnt happen. Harvey was useful against her, but not for long, as he was no longer horror immune to 1 damage monsters and just kept getting whittled down. When she hit the table I deducted 2 of each stat from each team member, and this happened in the beginning (turn 2) so they were able to soak it up (Harvey especially, but then he was down to 1 stamina and had to shamble over to St Marys).I dont regret dealing with her, but only just. As the team were almost wiped at the end, one little extra loss at that point would have sent all my plans down the toilet. Had that happened, regret would be written all over not dealing with her.