Don't know if it's mentioned in the AF Body write up, but in Beudeax (spelling) the Ruby Quadav will aggro even if you are sneak and invisible. I believe there are two other NMs that will do so as well.
Also bring plenty of echo drops if you intend to stay behind solo or duo BST after getting the key. You'll have to run from the "cross" room down to the bottom a few times scanning for coffers. Silencer > Curse thingy.
Took us about 4 hours total for two keys and two coffers and was heavily camped.
The AF is cute. I wish I could get my character's belly button pierced now (
)