Enlightened Hearthstone
Source: Other. You can obtain the even if you don't own the as anyone can interact with the while it is up.
The 
Enlightened Hearthstone is a Shadowlands toy obtained from a secret treasure summoned in Zereth Mortis by coordinating six players using the 
Sphere of Enlightened Cogitation.
Guide awaiting review
Obtain Sphere of Enlightened Cogitation
The Sphere of Enlightened Cogitation has roughly a 13% chance to drop from 
Enlightened Broker Supplies, the paragon cache from the Enlightened faction in Zereth Mortis. Note that you do not need to own this toy yourself to receive the Enlightened Hearthstone, as anyone can interact with the treasure once it is summoned.
Gather Six Players
Coordinate with five other players who each have the Sphere of Enlightened Cogitation. It is possible to solo this by using five free starter accounts, as there is no level requirement to use the toy, and refer-a-friend teleportation can bring those characters to Zereth Mortis, waiting 30 minutes between each summon.
Position Players on Platforms
Each of the six players must stand on one of the six hexagonal platforms surrounding the lake under the Forge of Afterlives in the center of Zereth Mortis at 47.54, 56.47.
Sit and Use the Toy
Once every player is in position on their platform, each player must sit down and use the Sphere of Enlightened Cogitation simultaneously to summon the secret treasure and unlock the Enlightened Hearthstone.
