The Mountain Roc is a boss and a core plot point in Golden Sun: Dark Dawn. It is a mammoth bird that roosts at the top of Talon Peak. While it slumbers, its composition is stone-like, and it can only be awakened by using the Slap Psynergy on its red wattle. Its feathers have the qualities needed for Ivan to create soarwings, and retrieving one of these feathers is the first objective of Matthew and his friends' journey. Also, magma energy within the bird's stomach naturally coalesces into jewel-like fragments called Magma Shards and, more rarely, a perfect jewel-like sphere called a Magma Orb. These fragments are usable as power sources to gain access into Belinsk Ruins, and the orb is the power source that is ultimately necessary for the Alchemy Dynamo within the ruins to be activated and unseal Eclipse Tower.
The Mountain Roc is considered to be divine by the beastmen of Morgal, with its image appearing on many beastmen structures, particularly in the city of Belinsk. Sometime before Dark Dawn, the Warriors of Vale traveled in search of it, with the assistance of Morgal's king. The Warriors of Vale were eventually able to get one of the Mountain Roc's feathers. The feather was used in the creation of the Soarwing, an invention of Ivan's that allowed an Adept to fly. One of these Soarwings was given to Isaac and Garet. However, when Garet's son, Tyrell, breaks the soarwing, a new feather was needed for the repairs. Thus, Isaac and Garet send Tyrell, along with Isaac's son, Matthew, and Ivan's daughter, Karis, on a quest for a new feather.
After a series of events, the party was able to reach Morgal, but realized that they had no information about the Roc. By this time, the group had met with Amiti, a Mercury Adept and the prince of Ayuthay, who had joined their party. Amiti had encountered the Roc as a child, describing it as a mammoth bird so large that it blocked out the sun. Later on, the party of Adepts were able to speak with Tret and Laurel, who give them vital information on the Mountain Roc. The Mountain Roc was then in a deep sleep, and could only be woken by means of the Slap Psynergy, a psynergy unique to beastmen. Additionally, the Roc produced a power source for the ruins in Belinsk, which would be needed for the group's secondary goal, to rescue Eoleo and Hou Ju, two prisoners of the beastmen. Before leaving, the Adepts were warned that the ruins hid a dangerous legacy, the Alchemy Dynamo, and were ordered not to start it.
The group eventually makes their way to Talon Peak, where the Mountain Roc roosts. Along the way, they gain the Slap Glove from Ryu Kou, prince of Sana and Hou Ju's brother. The party makes its way to the Mountain Roc and succeeds in getting a feather. However, Blados and Chalis, two Tuaparang commanders, set the Mountain Roc on them, for reasons they do not fully explain. However, they encourage the group to kill the Mountain Roc, and gain the Magma Orb that the Roc produced. Matthew's party is able to defeat the Roc, but Ryu Kou takes the Magma Orb for himself. Eventually, the Mountain Roc's Magma Orb is used to awaken the Alchemy Dynamo, which starts the Grave Eclipse. After this point, the Mountain Roc plays little role in the plot.