Dia (ディア, Dia?), also known as HARM or Dia1, is a recurring spell in the Final Fantasy series.
Initially appearing as a White Magic spell meant to deal damage to undead enemies at the start of the series, the lifting of the original Final Fantasy's strict targeting restrictions has resulted in its original function being folded into the Cure line of spells, which have the same effect when used on undead targets. Its later appearances in the series usually deal minor holy-elemental damage to enemies.
Appearances
Final Fantasy
Deals damage to all undead foes.Description
Dia (HARM on the NES and Dia1 in Final Fantasy Origins) is a level 1 White Magic spell that inflicts minor damage against all undead enemies. It has no effect on other types of enemies. In the NES and Origins releases, it inflicts between 20 and 80 damage, while in subsequent releases, it inflicts damage depending on the caster's Intelligence.
The spell can be bought while in Cornelia and can be learned by the White Mage and White Wizard classes. In the GBA/PSP/iOS releases, it costs 5 MP to cast.
Final Fantasy XI
Dia is an Enfeebling Magic spell that can be cast by low-level Red Mages and White Mages. It deals a very small amount of light-elemental damage and applies a status effect that reduces the target's Defense and deals one point of additional light damage per tick over the course of a minute.
Final Fantasy XIV
Dia is a 
White Mage spell learned at level 72. It deals direct unaspected damage with a potency of 65 when initially performed on the target, followed by a damage-over-time effect with a potency of 65 for 30 seconds. The spell costs 400 MP. The 
White Magic Mastery trait increases both the potency and damage over time potency to 85.
Final Fantasy XVI
Dia is the magical spell cast when Bahamut (light-elemental in this game) is the currently equipped Eikon. It becomes the more powerful Diara if the player charges before casting the spell. Like other spells available to the player, it only does non-elemental damage, as the game does not have elemental weaknesses or resistances. The Eikon-attunement is thus merely cosmetic, but the spell appears white-blue when it is Dia or Diara.
Final Fantasy Tactics S
Pictlogica Final Fantasy
Dia is a rarity 1 Black Magic spell that deals minor Holy magic damage to one enemy. It has a maximum level of 6, an initial charge of 45, a maximum charge of 35, and an effect of 10.
Pictlogica Final Fantasy ≒
Final Fantasy Airborne Brigade
Dia is a spell with a base Attack of 670, and base Defense of 710. Its maximum level is 60, its cost is 11, it is an ability based on Intelligence, and it has a fast leveling rate.
Final Fantasy Record Keeper
Stranger of Paradise Final Fantasy Origin
Final Fantasy Fables: Chocobo's Dungeon
Dia is a Level 3 spell that can only be cast by Chocobo as a White Mage. It inflicts medium Holy elemental damage to one foe three grids forward, costing 2 SP to cast, and 120 JP to use.
Gallery
Etymology
Dia means "day" in Portuguese, Spanish, and Occitan.
In ancient Greek religion and folklore, Dia means "heavenly", "divine", or "she who belongs to Zeus". The name is attributed to several figures and treated like an honorific or title.
In the original Japanese release of Final Fantasy, ディア (dia) was an abbreviation for ディスペル・アンデッド (disuperu andeddo, "dispel undead"). When it was later realized that dia and día mean "day" in Portuguese and Spanish, the name was applied to other localization as a play on the idea that sunlight is harmful to the undead.[1]