My post was just for six hours straight in one place. I did every triumph required for the title in this last week and got two of the overlords, except for the hellmouth. I went to spawn the hellmouth one, and it wouldn't spawn. It went on like that for six hours. It shouldn't take six hours, I did like 25 vex invasions, to spawn an enemy I'm capable of killing by myself in literally two minutes. It was the last thing. I knew people who spent weeks trying to get them to spawn.