Full of misinformation!
"*Damaging Seth is no easy task. The only way you’re even going to touch him is with a bow so forget everything else. Magic is usless, too.*" - the walktrough says.
What a nonsense, I've just killed Seth using Hellfire. Well first I did score a couple of shots with fire bow, but then Seth started moving so fast that shooting at him with fire bow became awkward so I switched to Hellfire and after a couple of shots he was down.
While which weapon is most convenient is up to opinion, claiming that magic DOESN'T DAMAGE SETH is simply wrong.
"*First, save up 1500 gold and then head to the western beach and pick up Bow Lore. (It’s under a tree you have to burn with Fireball.) This is practically essential because you can’t damage the boss goblin without it.*" - the walkthrough says
Another nonsense of the same sort, IIRC I killed the goblin boss using EXCLUSIVELY magic.