Tree of Transformation is a kind of tree found in Hexxit. Galactic letters (same letters as these ones in Enchanting Table) are falling from leaves of these tree.
Maybe it has something with Twilight Forest Mod, becuase of Transformation Powder.
Unknown usage, probably for special kind of wood or the Transformation Powder.
When standed nearby, it can somethimes make sound like you are in nether portal.