Spirit of Eche'ro is a new added Archaeology ghost version of Reins of the Grove Warden, also is the third Archaeology mount after Scepter of Azj'Aqir and Fossilized Raptor. The difference is Spirit of Eche'ro is easier to acquire, while Scepter of Azj'Aqir and Fossilized Raptor all require a specified Archaeology Fragments which need good luck to get mounts. Spirit of Eche'ro is rewarded from the Archaeology Quest: Laying to Rest in Highmountain.
After you get to level 110 and open the World Quest, you can pick up an Archaeology mission every two weeks, then discover rare archaeology relics. It is the only way currently found on Broken Isles to gain rare archaeological discoveries. You will acquire your Spirit of Eche'ro in highmountain by finishing archaeology quests. Just get the quest when cooldown, and complete it. But if you missed the quest, need a long time waiting till next.
Each map corresponds to different types of archaeology, for example, The Stormheim to Demon, Azsuna to High Elves, Highmountain to High Tauren. Each map will offer different rare gears, items, toys, rare props or items that worth 5,000 WOW Gold. Compared with the previous Archaeology achievements, Legion Archaeology acquiring saved much time.