Sreng would be easier with a warrior and ranger combo with the warrior running adds and ranger hoping bolas doesnt miss.Should give the High Priest (160) a try, I imagine that would be easiest
Also, I'd say with Sigils - Rogue and Ranger duo would be the best shot. Rogue could expose the boss making fewer bolas' miss, as well as solo-clearing the adds and sig'ing up whilst Ranger focused on boss and Rogue hit the boss up in between adds. Very do-able but would be good to watch
The hardest would be King/Snorri tied for first place because the kings adds are just sooo op at their lvl and snorri for the hard 1 hit skills and troll adds.