u/Dependent-Machine161

I'm really just a little away from completing 100%, I'm missing a few challenges, Roberto's cape and Cl4nk's cap. Regarding this, the challenge asks to kill a boss in less than a 1 second. Any advice on how to do it? At the moment, every attempt of mine just gets close; I can destroy some bosses in 5-10 seconds, but I can't do 1 second.