Everburning Crystal

Everburning Crystal unlocks the Frostfire Remembrance appearance for the Ebonchill artifact.

Source
To obtain this item, you must have selected the Order Hall trait Teleportation Nexus (trait). There is a small chance each day that the portals from this trait will instead send you to Frostfire Ridge, where you can loot the Everburning Crystal. You will be alerted to this chance by an emote when walking around on the stairs of the Hall of the Guardian.