http://divinity.wikia.com/wiki/Armor_sets

According to the wiki and a few posts that I've read, you're supposed to get the helmet during the Down the Hatch quest. I just finished this quest, and I didn't get the helmet. I got a Crystal Dragon Helmet instead. I also tried looking around Kali's fortress, but I wasn't able to find the helmet there either.

So I'm wondering, where am I supposed to get it at? I have all of the pieces except for this one.