First entry: from the wither zone
Finding the first entrance is not easy, because from a distance it looks like a small depression in the ground and is covered by a tree. You can navigate on the map. On it, if you look closely, you will also see a depression that corresponds to the entrance to the cave.
The appearance of the location depends on whether the Wither zone has been eliminated or not. You can see the cleaned up version of this section above.
Go under the branches of the tree. If the Wither zone has not yet been removed, you can navigate by Tumor . In the cavity there should be either an already open path forward, or a stone blocking the passage . To remove it, summon the Dendrogranum , approach the cobblestone with the seal and make a charged attack by holding the left mouse button.
If you jump down, you will get to the Gate of Dreams , from which you can go to the flooded area or other exits. You can also find one of the automatons needed for the Legends of the Stone Castle quest here.