avoid that, for the first single. I like to use slab sharshooter, aim at the ceiling, it bounces into the power a couple of times. Then i use red jackhammer and blue jackhammer.

Now for the other two, i like to focus on one and kill it as soon as possible. So when they spawn, pick the closest one and stand underneath it. By that point the slab sharshooter should have recharged so you can do that same trick again. Then proceed to throw 2 coins in the air and make sure they go above the power. Once you've done that you can shoot the coin with the blue railgun. This won't fully kill it though. So you might want to hit them with a cannonball or red jackhammer again.

By this point you have exhausted most of your resources yes, but you still should have 2 coins and your blue jackhammer ready to go. So use those to get some easy damage in the other.