Do you mean you've already dealt with them or that Williams keeps running into them? If the latter, I'd recommend starting again and deal with them yourself before talking to Williams.
I did have problems trying to keep all three alive (no particular reason, I just wanted to) as the half dozen extra Black Ring tended to overwhelm them, but several attempts as well as getting my pet gristle (er, whatever the necromancer's creation is called) involved eventually did the trick. If you have any summoning skills they may also be worth a look.
Reducing the difficulty for the duration may also help, though I personally already had it on minimum because I'm hopeless at combat!