Last Day on Earth Bunker Alfa 2nd Floor Beginning taking no damage
Quick clip showing how to do the beginning of the 2nd floor without taking damage. Other videos I've uploaded I forgot to start recording for this part, and I've seen several people asking how to easily do this part.
All you have to do is bring a crusher and swing then backup until the delay in between swings is over, then hit attack again. Sometimes you'll take a little damage just because the zombies grouped up, but it's always minimal.