I avoided them until i get a chainsaw. Honestly, i avoided nearly every monster until that. On level 3, 4, or 5 take a look, if there are stairs to The Chained Court, without chainsaw AoB is impossible, i think. But then there will be levels with less sergeants, and more other monsters, who are not so problematic to kill. You will get normal armor also. I advise you to pick Tough As Nails*3 after picking two perks of Brute. Then i picked Iron Man*3, last Brute, and one Eagle Eye, found LS, and AA, and with all of this i became nearly impossible to kill.