Yuslan Sha'Rim is a Qyranian arcanist working under Constantine Firespark's Nehrimese mage order, helping The Holy Order fight against The Cycle. He is not very fond of The Order's ideals, and seems to talk with a nonexistent woman called "Näea" during his dialogue.
Motivation & Actions
Yuslan was a resident of the village slaughtered by Grandmaster Tealor Arantheal during The Night of a Thousand Fires, where he managed to survive (or perhaps not, see Nature below.), while his child Lina and his wife Näea were killed. He swore to have revenge on Arantheal, and joined Narathzul Arantheal's fight in order to get closer to him. After coming to Enderal to "help" The Order, he made sure to hinder their plans: He sent mercenaries to attack Old Rashêngrad, gave insider information about scouting posts to Taranor Coarek, and killed Lishari Peghast after she found out about his wrongdoings.
After all of his actions were undone by The Prophet, however, he had one more trick up his sleeve: To take away everything from Tealor, at the last moment. As he entered the memory of a High One during The Shards of Order, Part II, he revealed his motivations and destroyed the Word of the Dead, eradicating the only known source of a Numinos, and therefore rendering the Beacon useless.
While it is never explicitly revealed, there is a heavy implication that Yuslan is an Emissary. His only motivation is to take revenge on Tealor, as he is able to sacrifice the fate of the whole world and his own life to take revenge on the Grandmaster. Not only that, but it is very unlikely that he, as a normal citizen at the time, was able to survive The Night of a Thousand Fires, as his whole family was slaughtered. Also it seems like he had a magical outburst of his powers like The Prophet had after his death during the quest It Starts with the Dreams, since he has became one of the most talented mages on Vyn. His actions had a direct influence on the triggering of The Cleansing, and there were others exactly like him in past iterations of The Cycle, as seen through the Echoes of the Past, which further indicates his status as an Emissary.