I got super lucky and Dammon dodged two hits, giving me enough time to get into the battle. The ox was fully turned into an enemy--completely unprovoked. I did a quicksave and had to save scum a few times since Dammon was first in queue and would instantly die if hit. I got lucky again and he dodged it after several saves, then I was able to get him to safety while drawing all the aggro towards Karlach.
I really hope they patch this soon. If they don't doing Karlach's quest will be incredibly difficult and unnecessarily stressful...