I find them extremely useful in bossfights where the boss keeps adding in stacks of creatures. They can be used to make a bottleneck or to prevent troops from being spawned behind your ranged fighters. I got about 1/2 a level (nearly 35K exp) by letting the spawns pile up while I killed the boss at my leisure. Since I don't have resurrect I used cursed ghosts and sacrifice to keep the other exposed troops topped off. (With stone skin and the physical resist boots, cursed ghosts can have 95% physical resistance!)
