Why were 3 demons sent to distract the sisters? Even without the distraction if the sisters attacked the demons they wouldn't have been able to destroy them without the potion, as when the demons first appeared it took time Leo to get the potion to the girls. The demons could have just shimmer in the basement and took Pirelli for like 5 seconds. Which brings the next question - why two upper-level demons will go to retrieve a mere mortal who is unconscious? There was no need for both Cole and Tarkin to take him and shimmer out with him.