Involvement
Like the other Masks, the Mask of Servitude wanders around the basement area. If the party either did not discover that Ethel was impersonating Grisly, or antagonized Ethel upstairs, then they will all be hostile. However, if the party agreed to Ethel's deal as part of Gather Your Allies then they will not be hostile and can even be spoken to. Mask of Servitude claims that she used to be ugly until "Auntie made her beautiful".
If the party confronts Auntie Ethel in the basement's next-door room, then she and other the other members of the flock will be teleported into the battle as long as they weren't previously killed or knocked out. They will be hostile by virtue of the 
Whispering Mask, placing them under the charming effect of 
.
If the party manages to encounter Mask of Servitude after Ethel is dead, she will no longer be hostile, but her sanity will no longer be intact.