will prevent this problem, but unfortunately if it has already occurred in the save it will not undo it. However, if you email your save to firstname.lastname@example.org, with a description of the problem, they can fix it for you.
If you have time to react when the conversation ends, the Hide in Shadows skill might help, with your creature and possibly a summon hopefully taking care of Xanlosch (or at least keeping his attention). A Stun Arrow, or possibly a Rush Attack, or something, may let you finish him off before he can hit you.
One person who ran into this problem used CheatEngine to fix their health until they got past Ba'al (someone mentioned that Steam may have a problem with the use of CheatEngine, though, even with a single player game).Where's the trick to Ba'al?[Not Sure if Bug][Spoilers]Killed Instantly
See Lar's post here
on how to send them an Xbox save.
With the PC version, in XP the saves are in the folder
C:\Documents and Settings\ %username% \Local Settings\Application Data\Divinity 2\Savegames
or in Vista / Win 7
C:\Users\ %username% \AppData\Local\Divinity 2\Savegames
You may need to set Windows Explorer to show hidden files and folders (XP, Vista
, Win 7