Hobgoblins of the Mailed Fist

From publisher blurb:

The crumbled ruin of the Watchtower of Auku Vaino has long kept a lonely watch over the wild borderland. Now, reports of heavily armed warriors camped at the site and sightings of something huge flying across the night sky have terrified the local peasants. Has bloody war come to the borderlands? Will all soon be in ruin? Who will shield the borderland folk?

Easily adapted for virtually any other setting.

This System Neutral Monstrous Delve presents the atavistic gnolls of the Bleached Skull tribe, along with a detailed overview of the dungeon below the Hill of the Sunken Skull.