From the announcement:
Fantasy Flight Games is proud to announce Oath of the Outcast, the first Hero and Monster Collection for Descent: Journeys in the Dark Second Edition! Oath of the Outcast offers you new options for exploring the potential of noble heroes and the overlord’s deadliest monsters through a new form of expansion.
Oath of the Outcast introduces four heroes and three monster groups previously only available in the first edition of Descent: Journeys in the Dark, as well as two brand-new quests. Trenloe the Strong, Laurel of Bloodwood, Elder Mok, and Shiver join your quests as eager heroes, but even as they enter your quests, monsters arise to attack. Oath of the Outcast includes three monster groups: bane spiders, beastmen, and razorwings! You will also gain two new quests in this expansion: Oath of the Outcast and Prison of Ice and Lies. In these quests, you will attempt to stop the perpetrators of a dark ritual from reanimating a host of powerful undead warriors.