Rift Quest:Spying on the Endless  

The Unseen Agent is a corpse lying on the ground in the northeast corner of the Iron Fortress (6999, 5325). She is guarded by an elite Endless Fleshfiend. To finish the quest, first walk close enough to "discover" the agent's body. Next kill the Fleshfiend and avenge the Agent. Lastly, the body will now sparkle indicating that it is lootable; be sure to "collect" the body. The Fleshfiend hits hard and has over 4k hit points, so bring a friend.