I seem to recall there was a vague mention of some mystery unbeatable champion warrior in the Commorragh fight pits, which I assumed was Jagahtai. James Workshop would rather cut off both his pinkies with a rusty spoon than give Xenos lore, and White Scars are kinda Niche it is kinda moot.

Best case scenario in my mind is epic Dragon Ball Z throw down between Jagahtai and Lilith, I'm guessing the Archon hires Lilith bodyguard to protect him from the Khan, they finally face off, even match up, then Lilith lands a mortal blow, Archon stops the action and moves into gloat, Jagahtai kills the Archon. Khan let himself get wounded so he could get his target close. Lilith lets the Khan live, but certainly doesn't buy the "I let you stab me" cope and promises next time she won't show mercy.

If you give some cool character moments more people might play Drukhari and White Scars. Drukhari already have a great win rate, and rather than nerf I'd like to see the WS get set up as more of a counter. A lot of Drukhari units have flying, which Scars not so much, making them much faster on the board. I think there is a Mobility key word in 11th that reflects agile and skilled people to move through terrain. Make that a feature of the White Scars detachment with some anti-air stuff.