This may be a dumb question, but... what's a drudge? The adventure has the stats for an alchemical drudge, and a brief description of their appearance ("like large, wingless homunculi"), but gives me very little idea of what the creatures actually are, how they behave, or how to use them in the fight.
I can't find it in any of the bestiaries (seriously, I've gone all the way back to D&D 4e looking for it), but the adventure seems to assume I know the word.
I think the only description is in the "Creatures" text before the statblock. They seem to be unique creatures created by Vilree.
...she experimented to create larger, smarter, and more capable alchemical servants. After a year of research, the first alchemical drudge was created. Appearing like large, wingless homonculi.... They have strict orders to attack anyone who enteres unaccompanied by Vilree.
I'd start with the description of a homunculus and make it bigger and smarter. The word "drudge" itself just means someone obliged to do menial and tedious work.