WoWDB

This item unlocks the hidden appearance called Frostfire Remembrance for the Frost mage artifact,  Ebonchill.  You must have the Teleportation Nexus talent unlocked for your class order hall, which unlocks a set of five portals.  There is a low, daily chance that you will hear a sound and see an emote alerting you to hearing something come from the portals downstairs.  Any of the five portals, at that point, will take you to a phased version of Frostfire Ridge.  An NPC will give the item to you.