You need to do the following steps:

1- Attack the blower
2- Once his purple bar is about to fill up, use BOOM BOX to interrupt it.
3- Kill blower first then move to Spitter ( knights will follow you )
4- When the group is clear, WAIT FOR BOOM BOX TO RECHARGE, then move to next group.

Spitters can't attack you if you go melee them, so if you are facing your last spitter and tim e runs out don't panic, just stay close to the spitter and you are good