The chest looks like this:
It is located in 1 of the 30 locations in this guide. You will probably not miss it :)
Celestial Essence: will help you summon Callagadra, Scion of the Sands. Happy hunting!

From the Korvan Plateau head straight to the West and into the Crawling Nest



















You can now check the #1 spot, the path is straight forward from the entrance.

From the Temple of Osyr Rift head towards West and check spot #2. Teleport back to the rift and head North for spots #3 #4 #5.
If you didn't get lucky teleport back to the rift and head East and into the Tomb of Osyr #6. Continue through the Tomb of Osyr until you get to the 2'nd level of the dungeon.



























Once you've reached level 2 of the dungeon the path towards spot #6 is simple and short.

Take the path South of Korvan Sands Rift and into the secret area containing Forlorn Bastion Entrance #7. Once inside proceed to the 2'nd level of the dungeon.
Once you reach the 2'nd level of the dungeon, spot #7 is right around the corner.

From the Cairn Docks Rift follow the path to the East to check spots #8 #9 #10.
If as always you weren't lucky teleport back to Cairn Docks Rift and head towards Sandblown Ruins Entrance #11. Proceed once again to the 2'nd level of the dungeon.





























On the 2'nd level of the dungeon go straight to the other end of the map where you will find spot #11.

From the Sunbane Oasis Rift take the path towards North-West and under the bridge towards spot #12.

From there go back and now cross the bridge going towards Sanctuary of Horran #13



























Inside the Sancutary of Horran the path towards the spot 13# is very easy.
If once again luck wasn't on your side teleport back to Sunbane Oasis rift and head North-East towards the Hollowing Chasm #14.






























Inside the Hollowing Chasm you will find spot #14 right around the corner. No luck? Proceed towards North-West to the secret area called Hollowing Depths #15.

























Inside the Hollowing Depths path is very straight forward to spot #15.

From the Runis of Abyd Rift go East and into the Tomb of Ateph #16.

























Insed the Tomb of Ateph spot #16 is right across the entrance.

Infernal Wastes is packed with locations to check. Following the path to North-West you can check spots #18 #19 #21. If none of them had the chest teleport back to the Rift and head straight North into Tomb of Sethan.



























Spot #17 is very close to the entrance inside the Tomb of Sethan. If this one is also empty head back to the rift and towards Tomb of Ariath.


















Once inside the Tomb of Sethan spot #20 is very close. If you still didn't find it time to go to #22 Tomb of Nephos































Once again Tomb of Nephos has a easy path towards spot #22.

Form the Lost Oasis Rift take the only available path towards the Tomb of the Heretic #23







































In the Tomb of the Heretic you will have to take a curvy path to spot #23.

Head North from the Korvan City Rift and you will find spots #24 #25 #26.

Inside the Tomb of Eldritch Sun head on the highlighted path to spots #27 #28 and proceed to the 2'nd level of the Dungeon #29 if you are the most unlucky person in the world.



































Another curvy path awaits you on the 2'nd level of the Dungeon towards spot #29.

The Eldritch Gate Rift Here lies the last and final spot #30.