Never managed to kill any of the big baddies in the first game. Decided to give it a try in Deadfire what with turn-based being an option. My first attempts at Jadaferlas did not go well. But once I bothered to spend 20 hours specifically outfitting my party with a million tools just to kill her, it ended up being disappointingly easy. HOWEVER, some of that seems to possibly be due to bugs. Once I finally won the fight, I decided to repeat it a few times, just to try it out. Here's a list of stuff I've encountered.

1- Sometimes she doesn't bother summoning magma oozes. I interrupted her first attempt to do so, and then she never tried it again. This is pretty inconsistent though. I'd say of all the times I redid the fight, this only happened once or twice.

2- Sometimes when the magma oozes spawn, they all spawn in the exact same spot and becomes stuck inside each other. This makes it very easy to AOE them down.

https://www.youtube.com/watch?v=BMfIrpU2Xog

3- Sometimes she skips her turn for no apparent reason. I think this seems to occur only if her last action was interrupted, possibly by procs from Deadeye.
Here is a video clip showing her skipping a turn.

4- Once the fight has been going on for a certain amount of time, all sound starts to become buggy. It sounds like listening to a damaged VHS tape. I have had a similar effect happen when alt-tabbing, but that version usually goes away once I've returned to the game window for a solid 10 seconds or so. This one, however, will start after I've been in combat with Jadaferlas for a long time, and does not go away until the fight ends.
 

Yes, I did have the sound bug the last time I fought her which persisted throughout the fight. It fixed itself when I left the area.