How about him spawning in one of these locations? If in the open world he could be under a large WoD that would blind any enemy that walked into it. Or he could just be in an area that never spawns adds. I'd much rather hunt him down in the open world like in some cave or in the open field than in the tower. I think this would add a ton of fun to the game trying to see who could find him first. If he were in the nightfall or weekly he could be either somewhere hidden in those areas or show up when you beat the mission and disables the countdown to space. You'd have to initiate the transition to space. Thoughts?