A really cool concept! I enjoyed the mechanics of patrolling and waypoints, though the souls seem to ignore units that aren't moving, which was a little frustrating. The red clouds and the hell hounds added a lot to the gameplay loop as well!
There were a few souls that seemed to get stuck on the bottom of the screen; they could move horizontally, but never came up higher, even when two units boxed them in from either side. The clouds at the edges also sometimes obscured my units or the souls, which was unfortunate.
But really, overall, this is very good. Well done!