Dranko was a thief, and a member of Felix's crew who went into the Bonehoard to acquire the Horn of Quintus. According to Sutter, Dranko had succumbed to the deadly breath of the Burricks, but it is possible that Dranko is the unidentified thief who went in search of the more valuable Mystic's Heart. He (the unknown thief) was aware that he needed to find "a room of statues, whose gaze is death," but he accidentally went to the wrong room. Trapped by the burricks below, he eventually starved to death.
The name "Dranko" was an Easter egg added by designer Dorian Hart; it's the name of a character from his long-running D&D game.