My PCs fumbled their roll with Iggwilv, and they might just try fighting her once she releases the aspect of Obox-Ob. I'm trying to avoid a TPK. I suppose they have the ring of 3 wishes, which will help somewhat. Maybe she could just turn them to statues or otherwise subdue them.
If they don't fight her then, they might fight her when she tries to take Demogorgon's aspect. The PCs know they will be hunted by Ahazu the Seizer without it (unless the corpse without the aspect counts for something) and don't know Iggwilv might be more powerful.