Actually, this was Annan's first time reaching the Bone-nurturing Ground with his own body.
In the "Thermal Illusion" nightmare, or rather "Gemini" nightmare, he had reached the vicinity of the Bone-nurturing Ground before.
Of course, at that time, it wasn't called the Bone-nurturing Ground.
Instead, it was respectfully referred to as the "Grey Tower".
It is worth noting that the word "grey" in the Elves' language also means reflection or shadow – the logic is quite straightforward. If black signifies "darkness," then grey, being "impure black," signifies a secondary level of "shadow."
Another name for the Grey Tower is the Tower of Reflection.
The so-called reflection must have an original form before being mirrored on the lake.
If we regard the ground as the lake surface, then the Grey Tower is the "Wizard's Tower in the shadow".
