Doploon

 is a quest item.

Obtaining

 * Dopple
 * Defeat the Dopple at one of the Class Temples, then speak to the Dopple Trainer.

Uses

 * Exchange
 * 1 with your class Dopple Trainer to get the Special spell for your class
 * 1 with a Dopple Trainer to get a Bunch of Keys
 * 7 s with a Dopple Trainer to ???