Title says it all....If you've played it you know that around 8 of the 20 waves, you have to deal with over 100 mobs. Most of them are runners, but the last wave is impossible to do with around 30 chargers, 40 sprinters and 20 tanks. I've tried it with almost every tower at the front and back at level 3 and all weapons upgraded to 6. And I can't even put a dent in the enemies. They just overrun you and destroy the core from 100% to 0% because each monster takes 10% or more away from the core.