This is an improved version of create herb spell. Faster but more expensive to
cast, this spell can create any herb known to you. The trick is, the herb must
be in season to be created. Usage: cast greater create herb at <plant>. Use
plant lore at list to get the proper herb names. Please note that creating the
most rare herbs can be very taxing on your magical might as Gaia is not too
eager to part with such wonderful treasures.