The Prisoner of Skull Hill

Publisher blurb: A Chelish outpost deep inside the anarchic orc-controlled Hold of Belkzen has gone silent after strange fires were seen burning in the skies above. You have been sent north to investigate the disappearance and find a lost tomb long rumored to exist beneath the outpost's timber tower. When you arrive and find the place choked with monsters and hideous plant creatures from beyond the stars, your mission of exploration quickly turns to one of survival.