Rift Quest:Frozen Gauntlet  

As soon as you use the Horn at the Guardian's Spire you will be attacked by two Undead Guardian Sentinels and the frozen river becomes lined with an energy field that will not let you leave. As you head west to the three shrines you will be attacked by more groups of Undead. Each Shrine will be defended by an Undead Icewatch Watcher. All the mobs are level 50 but the larger the group the weaker the members will be.