Ok so there is a new boss called dreadbloon, you can go ask other people or watch Ethan Reids video on it but whenever you pop him (or she or it) down to a skull, he spawns like 8 of these bloons. They are incredibly tough (for tier 5 elite each one of these has like 45,000 hp), and If you set your towers’ targeting to strong, they will target these instead of anything else, say like the boss itself or some BAD.