Rift Quest:Rise and fall  

Work your way into the main square, taking out the roamers first of you can. Don't bother with the corpses yet, because when you are burdened with a body you get very slow. You can still fight, though, if you have to. When you get a body to the pile, click the icon in your Quest Tracker to lay it on the pile. After the fifth body has been added, use the new icon to purify the bodies.

Next, in the archway to your left is a Dark Necromancer. Kill him and move to the archway and Corwin Mathos will appear and show you what happened here.