Thunder (Final Fantasy IX)

Thunder is a Blk Mag spell in Final Fantasy IX for Vivi that deals low Lightning-elemental damage to one or multiple enemies. It can be learned early on if the player nets the Silk Shirt for impressing 88–99 nobles in the sword-fighting minigame or steals it from Steiner. If Steiner and Vivi are in the same party (and neither is incapacitated in some manner), the former can also use Vivi's Thunder spell in his sword magic, where the ability uses his stats rather than Vivi's. In Trance, Vivi can use the spell twice in one turn.
The Black Waltz 2, Black Waltz 3, Ghost, Plant Brain, Plant Spider, Python, Skeleton, and Type A can all cast the Thunder spell. It can be reflected as normal and can be countered with the support ability Return Magic.
==Obtain==
Thunder is learned from the Glass Buckle and Silk Shirt for 25 AP. Glass Buckle can be synthesized for 500 gil, a Glass Armlet, and a Leather Wrist at Lindblum, Treno, Alexandria, and Black Mage Village.
Silk Shirt can be bought for 400 gil at Dali, Treno (before going to the Outer Continent), Lindblum (after the invasion of Burmecia but before going to the Outer Continent), and the Black Mage Village (before entering the Shimmering Island), found in Alexandria from Brahne (beginning of the game) by impressing 80–99 nobles during the play, and stolen from Steiner or Black Waltz 1.
The earliest to get it is from the sword-fighting minigame during I Want to Be Your Canary near the beginning of the game, but as the Silk Shirt is not the best reward, it is always better to forgo it in favor of the Moonstone. The best early source is from stealing from Steiner during the play's climax; Vivi can then equip it for use in Evil Forest and learn Thunder.
==Mechanics== 
Black Magic spells are based on Vivi's Level, Magic stats and the Spell Power of the spell. Vivi can use the Focus ability to increase his Magic during that battle by 25% per use. The effect stacks up to 99 and lasts for the entire battle, even if KO'd.
:Base = 14 - Target's Magic Defense
:Bonus = Magic + RndMOD ([(Level + Magic) / 8] + 1)
:Damage = Base * Bonus
Where Rnd means a random number, while MOD means modulus operation. "Rnd MOD x" can be read as a random number between 0 and x-1.
Bonus is halved by Shell, being under Mini, and if the player multi-targets the spell. Bonus is boosted by 50% if Vivi equips Flash Hat, or if Steiner equips Thunder Gloves for his Swd Mag.
In Vivi's Trance, Blk Mag turns into Dbl Blk where Vivi can cast two spells on his turn. The spells cost MP and expend the Trance gauge independently.
The support abilities that affect Thunder are Reflect-Null (Thunder pierces target's Reflect), Reflectx2 (Thunder deals more damage when reflected), and Mag Elem Null (Thunder deals non-elemental damage). 
For Swd Mag, damage dealt is based on Steiner's Attack and Strength stats, as well as on the power of the spell. Using Thunder Sword boosts Steiner's Attack by 5 and inflicts Thunder damage to one enemy.
The damage formula for Swd Mag spells is as follows:
:Base = Attack + 14 - Enemy Defense
:Bonus = Strength + RndMOD ([(Level + Strength) / 8] + 1)
:Damage = Base * Bonus
==Use==
Thunder is Vivi's basic lightning spell and thus is useful in the opening portions of the game. He can boost its power with Focus. It is especially good against enemies weak to the Thunder element, such as Gizamaluke or Armodullahan, though by that time, Vivi may already have the superior Thundara, though Thunder can still be used to save on MP. Aquatic enemies are commonly weak to Thunder.
As a Swd Mag, Steiner can use it effectively against enemies weak to Thunder-elemental damage. Though it can also be used generally as a straight boost to his damage output, given Steiner's much lower MP pool, he should use it less regularly than Vivi.
==Etymology==
Category:Black Magic in Final Fantasy IX