If you don't have the above mentioned spell, then I think you need +3 or better weapons to hurt it and even then you do the minimum damage. You really need to look out for the cloudkill it lays down around itself, so range weapons work well. I killed my first Adamantite golem with Azerudge and the cloak of stars
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Never try to teach a pig to sing; it wastes your time and it annoys the pig