Berserk challenge requires you to press every button whenever it is available to press, no matter how expensive or late it might be.
Expensive autopromote, late bias or even multi, throw all vinegar - doesn't matter, it has to be pressed immediately. This might bring you a Tank win on the ladder but also might hurt you a lot by multiing or biasing down close to a promotion_requirement.
Winning the round with this challenge is very possible, although constant vinegar throws make you an easy target.