i never attacked the ox on honour but i did noticed some differences between honour and tactician during some other encounters so i can believe that a lot of those change on honour. if you play as a sorc probably the best way to leave the ox be to the act 3 because you want to get alfira's robe in act 2 and iirc you need all the tieflings to be alive for the act 2 quest, and iirc again attacking the ox in act 1-2 can provoke nearby tieflings
