I just entered the volcanic and ash area where the Pyre of Man (I forget his name) lives. I was clearing out the smaller guys for experience and rewards, when the Pyre of Man attacked me. The problem is... he wasn't in the battle. I killed his many minions, and the battle ended. I got credit for killing him (he was on the list of monsters that died) and a huge amount of XP. When the screen went back to the map, I saw the animation of him fall over. But I didn't have to do anything. I am not sure why he didn't spawn.

I also couldn't capture that area and build there, even after I killed everything and explored everywhere. I am not sure if that is related, as it has happened to me often before.

Lastly, on an unrelated note, the volcano area there is REALLY dark. As the units notable areas are mostly the same color, they blend right in and it is difficult to see anything.