A letter on Brutus mentioned where Roiseadh "the mother", (aka the main boss) of the Sinister Seven would be waiting, up on the mountains just South of Falkreath. Deciding it was time to end this, Drania and I swung past Whiterun to pick up Twilight and Aurora and in no time at all, we were climbing up the slopes to meet her. Obviously she was a gimmicky boss too.
Other than summoning the usual horde of assassins which I let my companions take care of, the witch enjoyed use of mirror images and the fact that hitting her in melee caused her to go completely invisible (unlike the "predator invisible" of her mooks) and teleport in a random direction. Took awhile for me to cotton on to what she was doing, but when I did aura whisper was the correct tool to bring her down.
Must be a three eyed raven...
With her dead, I mopped up the remaining bounty hunters. Yes, while I was busy dueling their boss they had downed the sisters and gutted Drania like a fish. It was over now though, and no more bounty hunters would come. I was the last one standing, and at level 70 to boot! With the threat passed I returned to Morvunskar and finally set Njada free. After waving good bye to Sanguine, the two of us headed back home to Windhelm for some much needed R&R.
Homeward bound. ^_^