In the Murkmire Malevolence, Marx was rented by Ellenor Breatham to be used as a getaway vehicle. The party attached him to a wagon that they labeled as "Cliffsunder Party Supplies" wagon, big enough to fit them and the Murkmire Stone.
In exchange for rations and seeds given by , who spoke to him using Beast speech, Marx was able to maintain a steady temperament despite the chaos occurring in the Cliffsunder Museum of Natural History. Because he ignored the actions from terrified guards and waited only to ride off when the party commanded, their mission ended successfully.