Can confirm I am also experiencing this bug if I go to Last Light the Ox goes on a rampage that ignores turn based combat and kills Dammon.
This leaves my options as:
1.) Lose both Ox (who I don't know if he'll be relevant later) and Dammon
2.) Try some janky hail mary to save dammon but still lose Ox
3.) Avoid Last Light entirely which is extremely difficult being smack in the middle of act 2. (Random aside I tried to go to act 1 to vendor and Halsin just straight up left my party)
All of these are pretty undesirable I'd like both npcs alive for later content. This bug coupled with the save bug leave me pretty much unable to play the game until a hotfix is released.
