I had an idea of the dice enemy rolling randomly (either in place or as it moves), then stopping on a particular face, which telegraphs the next attack (perhaps the number of dots = the number of bolts, and is inversely proportional to damage) and lets the player anticipate their behavior. This might need the enemies to be less frequent but have more health, more similar to bosses, but starting slow and letting the player learn the enemy behavior means a lot more strategy in later stages!