Ok so I killed Ethel in a slightly sneaky way, you can just hide, or use Shadowhearts cantrip Pass Without Trace, to manouver and then just push Ethel off the edge, but you dont get anything for doing that. It works very well but I dont know what ive potentially missed by taking this shortcut so am now going to try and kill her legit, although its a hard and sometimes quite cheaty fight.
