I killed the goblins, camped, almost killed the hag by stunlocking her upstairs before she finally got invis off and ran, went through the guards, went back up and outside, slept, then went all the way back down, snuck around, used invis to lower Mayrina, she wouldn't talk, fought the hag (get as many multi-target ranged as possible, like magic missile and scorching ray to clear the grand illusions) she'll start her dialogue when the hag is dead, and all the items in the Witch's final grotto will be available.

Maximum XP gains laugh

I think the devs need/intend to make Mayrina pass out or something after leaving the cage, and then have an unbreakable spell tied to the hags death on the room door.