Edit: Time to condense my related questions in to one post.
Q187: I'm sure this has been beaten to death, but search failed me. What do you do with an Achorn of Far Travel?
So far I have Hathran, Earth Nodes (Node Spellcasting, Metanode being the key ones it seems), Sanctum Spell, Hallow and the very mundane use of making Rangers able to hide.
Q188: It says you count as being under that oak tree. Assuming that oak tree is on natural soil, does that mean you get your Earth Spell benefit?
A188: Right now I assume that this answer is yes, which adds Earth Spell to the above.
Q189: My dedicated spellcaster is always under a spell effect per the effect of Hallow (the hallow follows me around in a magic achorn). What spell should it be?
Q190: How do I grow an Oak Tree in the underdark? Or maybe find an earth node on the surface? Perhaps a big one just extends to the surface? The fluff seems to imply that they are all underground nowhere near oak trees.