88 Heroes

I found that room 34 was great for grabbing this. I started a solo run with POWERTRON the robot with a lightning bolt on it's chest and a missile turret arm. Right at the beginning of the level you'll find 10 turrets, run and jump onto the platform, jump again and fire to take out the three at the top right and continue down and go past them all. If they leave the screen they won't be able to fire in time. Head back and do the same on the other side. When that's done continue through the level blasting robots, chain traps etc and you'll rack up 30 kills in about 60 sec. When you're done killing the last four lizardmen just stand under the elevator and let it crush you or fire at a wall to blow yourself up.