Khan's Path

then the problem is that even after collecting all the obelisks, the entire map doesn't open.

Therefore, you have to dig everywhere.
The Grail is located somewhere under a tree, and, as far as I understand, specifically under the tree. The hero cannot stand on that tree, and digging half a dozen holes around it doesn't help (it's to the east, southeast). So, theoretically, only a hero who has taken the useless skill of Askh's patronage can dig up the Grail. Or is there a missed moment, a shaman nearby, and a dialogue was available. But what's the point? It seems that without Askh's patronage, you can't dig up the Grail.

Or has someone honestly dug it up? Then what's my mistake?