Unfortunately [for you] the t5 in SSC drops from the harder bosses. I don't see Karathress happening, since all the bosses would be grouped up together, and Vashj would be almost impossible [getting the tainted ele's to die on top of the towers seems like a reach]. Leo might be do-able though. KT phase 3 also seems out of reach for Priests to solo while we're on the t5 topic. Void Reaver? I have no idea but it's too bad we can't MC his trash and use them against him anymore.