Dia III lowers an enemy's Defense and also deals gradual Light-elemental damage. It uses 45 MP to cast, takes 2 seconds to cast, and 7 seconds for subsequent casting. The spells duration and potency can be increased by Merit Points and Job Points.
Like other Dia spells, it overwrites all other Bio and Dia spells that players can cast.
Behind the scenes
When originally introduced to the game, Dia III could only be learned by Red Mages level 75 and higher by spending 3 Merit Points to purchase it from the merit menu. Following the June 2019 patch update, Dia III was changed to become a purchasable spell in Lower Jueno.