From my experience, boss fights, at least the ones in the storylines, are heavy on endurance. I tried to do the final one for "Path of Thorns". You know, "Heart and Minds" where you fight two evil versions of your companions before fighting Mordremar? I realized I may have finally met my limits. I am 60 years old with a minor case of Parkinsons and this fight is probably too much for me to solo. I tried to solo this fight with my elementalist in berserker gear (the only gear I have right now). Fiddled around a bit with keybinds and aspects to squeeze as much out as I could. The fights were a constant run away, run away, heal myself and hope to get a few strafing shots off while doing so. I finally had to give up after 6 hours as my body was failing and my left side was shaking uncontrollably. I did get as far as phase 4 of the Mordremar fight, but I finally had to give up. This fight has taught me that boss fights in this game are probably a challenge best suited for young folks. I regret not being able to finish my storyline but then again, it is what it is and I really would not want to see this game made easier for someone like me. It would become much too easy for young folks. In my youth I think I would have had a blast with this but now, at this stage of my life, such endurance runs are just too punishing.