Halls of Serqet (Duat)
The mega-scorpion lair on the easternmost edge of Duat realm.
Note the white treasure box just north of the cave.
This is one of those rare 20 shard boxes, and shouldn't be missed.
Unusually, the entrance to the Halls is guarded. But from your high vantage, you can choose whether to drop down behind the guards, or annihilate them from on high.
Once inside, kill the local scorpion king to complete the location. There are a few bits of loose star shard here as well.
This is also one of the five Serquet locations that are required for the Sting in the Tale achievement.