High Priestess Levian:
To become an Elven Wizard, you must bring back the eternity diamond as proof of your worthiness. This means you have earned the right to become an Elven Wizard. If you go to the Elven village and meet the Elf Rosella, she will give you the test. You must pass her test to become an Elven Wizard. Since Rosella is in the village, it won't be hard to find her.
Return