My character is level 28 and I decided to try doing some flying fortresses. I entered the snowy one, don't recall the name, and am at a loss as how to go about it. I prefer human form to the dragon so I looked for places to land rather than take on all the towers. I spent about 30 minutes carefully pulling a couple enemies at a time at 5 different camps but didn't see any doors or bosses.
Is this mainly a dragon area? Are the bosses in human form on the outside or through a door somewhere?