I had too much cat food (pikes) with me so I decided to take off my earmuffs and found out the following, which would be a little more accurate than what's currently in the Bestiary regarding these Banshees. I noticed that within 4 hits, my Attack, Strength, Ranged and Magic went down with over 50 lvls, defence with around 25, prayer with almost 30 levels drained, and summoning around 10. Note: When you are not wearing your slayer helmet or earmufs, you will take 8 HP damage for every hit they make, as well as extreme losses in Attack, Strenght, Magic and Ranged stats, your Defence will also degenerate, but at a somewhat slower rate. Next to that, your Prayer and Summoning points will be drained quickly.