Shattered Kingdoms

In a recent battle against a large hp NPC, I was with a large group of undead. There were about 20 outside of the group. As soon as I encountered the NPC, another group began to attack him and I followed suit, by typing in my 'o all kill <NPC>'. However, after a few rounds, it became clear that we were doomed, and the leader of the other group fell. Immeadiately, my undead stopped attacking said NPC. I was quite discouraged when 3 seconds later, the NPC in question healed it's hp back up to it's full (very large) hp pool.

Sorry, no log. I can go into more details if needed.