The archmage staff actually was the specific artifact I was referring to when I mentioned the ridiculous difficulty of supressing some items...
I was a level 26 mage and the fight took a long time and sure wasn't easy. It took 2x Ice Snakes to destroy a single gremlin tower, and there were 6 of them plus a large starting army.
And by the way I'm more convinced than ever that there is something wrong with item morale. The morale of every one of my artifacts dropped like a stone while I was killing undead, and now I'm killing demons and all of their morale are slowly going up... Why would human/elf/neutral artifacts lose morale killing undead?! If all artifacts really have their own morale factors then it really should be officially documented. I tried to download the automatically translated russian fan manual but all the downloads timed out after a few seconds