Ah... Now you know whey I dubbed M*ry Worst Girl.
I never touched the corruption tree since I am very attached to MC keeping his femboy, untainted body.
But yeah, I hear some of the corruption skills are very powerful.
As for Llavanya's Fury, just think of that as a tactic to use during your next playthrough.
I'm guessing her weakness is the Best Girl weapon which is what I used to defeat her. Aside from that I would use Fury of Best Girl x5 outside of battle, rest at the fire than beat her down with your strongest weapon.
That makes sense. I think I used them against her on one of my earlier playthroughs. They did good damage but it was like having a Machamp use Fire Blast.