No, with the appropriate weapon, it takes 200-800 damage on each hit and it's more a matter of clicking away as fast as possible. Though I think Beo once mentioned in FC that someone (Ian Clark, was it you?) once killed that monster with a regular weapon. Normal weapons do like 3-12 damage on it.
On the flip side, I have NOT gotten a single level so far in this exercise...
And yes, those demons are a PAIN.
EDIT: Fiery Cerberus. A lot of people actually found it in ConfluxII. Ian Clark, Gambit, Antman and others. It's all in the archives... except exactly HOW to get it. But it apparently involves cheating, or at least trying to cheat. I have done many rule-bending things in Conflux so far, maybe I should do them in the presence of a cerberus, so it snaps out of its apathy? Also, it seems that the little guy growls in some instances. Mmmh, the plot thickens, I guess.
Funny thing is, I read you could once get a special ending by using the bone doll and the crown of Kings on the dark councilor, but Zyx took that out. I wonder what it was. I know another vestigial secret ending that is still in the game even though you're not supposed to be able to get it anymore, so maybe..? I can't get the bone doll in this game, but I had been meaning to restart with the cursed party for a while...