That's what I get for trying to be cheeky

[Quadsword]

On my current play through, I tried sneaking past all of Auntie Ethel's thralls since I didn't feel like fighting them (and thought maybe there was a possibility of freeing them without killing them). I get to Ethel... and on turn one, she summons all of her thralls into the fight.

I eventually won, but I ran through the majority of my healing supplies. I'm very glad I made Karlach a bear totem barbarian so she could tank all of the damage. Did manage to pass the speech check with Ethel after the fight, though, so I freed Mayrina and got a nice boost to my charisma (Draconic Ancestry Sorcerer).

Also, dumb question: When Ethel disguises herself as Mayrina, is there any way to tell her apart from the real one? I literally just guessed and happened to get it right.

[Metallicus]

Magic Missile scrolls will sus out the real Ethel quickly, but the fool proof method I use is to hit her with a flask of water and then she will always be the one with the ‘wet’ condition.

[Detective Costeau]

As for telling the fake and real Mayrina apart- the UI when you mouse over them tells you one is level 1, and one is level 5.

[Piperbird]

You can also inspect them all. It's been a minute but IIRC, the real one will say something like they're fae.

[Raz]

Various ways to tell them a part. For one, only Ethel has the Fey something passive. Ethel as Mayrina is NOT pregnant. You see the baby bump on the real Mayrina, not on Ethel.

For the masked people; just knock them out in the room they are in alone before facing Ethel then go back and remove their masks (don't remember them before she is dead). Long rest, and they are up and running.