Evil yuan-ti conspires to destroy a kingdom using dark rituals and the bones of a long-dead king. To win the day, heroes must storm the yuan-ti fortress and wrest the bones from the cultists' clutches before they complete their rituals and unleash a far greater menace upon the world.DD3 Fortress of the Yuan-ti is a Dungeons & Dragons adventure designed for 6th-level characters. The third adventure in a three-part series, it can also be played as a stand-alone adventure.