Great minds think alike! I actually had bishops 90% finished and they acted exactly like that (they were just missing visuals and being added to the spawners' lists). But I had to cut them for time since this was my first game jam and I didn't want to risk missing the deadline.
The enemy spawners are actually attached to invisible bishops that are set to ignore all collision other than the walls. Thats how the enemies spawn in "random" locations
Thanks for playing my game!