I'm almost not inclined to mention this as these are the toughest challenges for me so far (only done a few of them ), but tonight for some reason my party always had full health on the 1 hp challenges. I have no idea why this was, perhaps linked to the update? I've quit and restarted and its still the same. I've made some progress tonight - yessiree! Is this the same for everyone else? Edit: Dammit, seen this has been posted already. I need to check more thoroughly! Apologies again.
Once youve completed the campaign, you can replay each quest with restrictions like "all elves, no party deaths or only 1hp for your party members". You get a guaranteed rare treasure or better for beating the level (but no xp)