Kurn's Tower Leveling Guide
Once you're in PoK head to the Cabilis stone which is on the "Evil" side. The stone will take you to the Field of Bone. From the Field of Bone head northeast to Kurn's Tower.
Once you're inside Kurn's Tower you can start killing the undead. Stay near the zoneline, this is where you will be the most safe for the next few levels. All you really need to keep in mind for this level is stay away from the Burynai Sapper.
Items of Interest
Once you reach level 13 start killing your way up in the tower. You'll be fairly safe doing it at this level. You'll generally run into the same type of mobs while working your way up in the tower, the only variation is you'll be finding a lot more "Greater" mobs. Kill this until around level 15, then you can move on to Unrest.
To get to Unrest from Kurn's Head back to Plane of Knowledge and take the Kaladim stone to Butcherblock Mountains. Once you're in Butcherblock head south to Dagnor's Cauldron. Below is a map, follow my line to get there from the PoK portal.
Once you're in Dagnor's Cauldron head far south across the map to Unrest.