Mages of Mystralia (UP)

You can't get this til late in the game, after you found the four mage masters and learned from them and return to Haven to speak to Enchanter, he's the green... thing that owns the garden where you plant the bulbs. He'll tell you that you are now strong enough to use the Sky Crystal, and some more dialogue will show up, when it's done, you can take the Sky Crystal out of the telescope device. After you do so head off to The Rise, there was a door on the bottom area of the map that had a serpent on it that until now you couldn't open. Use the Sky Crystal to open the serpent door, behind the door is a chest, and in that chest is the Elixir.