From the Runic Portal in Aht Urghan Whitegate, take the portal to the Halvung Staging Point which will put you in Mount Zhayolm. Exit the Staging Point and head to the gate at (J-7). The Gates can be opened with the Cast Metal Plate (see link below to obtain this key item).
Once past the gates, you will see Wamoura, Wamoura Princes, and Sweeping Clusters, just beyond these mobs you will start seeing the Hilltrolls,the RDM hilltrolls are scattered mostly on the upper tier of the fort structure (7 spawn points) from G/H-7 to G/H-9. The link below is a map of Mount Zhayolm, near the circled 4 on the map is where the hilltrolls are located. Skyfiredancer (talk) 06:43, September 25, 2015 (UTC)