Adamantium golem is easy. Just use Azure Edge on it (got after the Copper Coronet Quest). As for Firkagg, do you have a fairly high level priest that can cast Harm. If so then use that to hurt him lots, then kill him with Magic missiles (it may take quite a few retries befor it works, but it deffinitely does work!)
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Nicodemus Deathslayer, Paladin of the Order of the Holy Flame