Dark Reign - Guardian of the Sands
Shogurei is the only raid mob this tier you'll have to actually go and find once you enter the instance. In the map below, I have his spawn location circled. He's a very easy boss, just comes with a ton of adds. Once you engage him he will start spawning goblins that run down from the northern room to help him.
They aren't raid mobs and can very quickly be dispatched of, I usually just ignore them until after the fight and then kill them. As with all of the other raids you'll be doing with DoN this is stupidly easy to do. After you kill Shogurei loot the item you need and return it to the Dark Reign camp, turning it in for a character flag.