Thunder III is an Elemental Black Magic spell from Final Fantasy XI. It is the third tier of the single _target Thunder spells.
Despite sharing the name in the English localization of Final Fantasy XIV, the abilities known as Thunder III in the title are in fact the recurring Thundaga spell in Japanese.
Obtained
The spell can be purchased from vendors in Lower Jeuno and Aht Urhgan Whitegate for 45,930 gil, and it may also be found as loot on several high-level, mage-class enemies.
Use
Thunder III is a tier III elemental spell that deals Lightning-based elemental damage to a single _target. It serves as a preferred method of inflicting lightning damage to single _targets during the level 60 - 80 leveling period for the pure casting jobs that have access to the spell.
Other appearances
Pictlogica Final Fantasy
Final Fantasy Brave Exvius
Etymology
Thunder is the sound caused by lightning. Depending on the distance and nature of the lightning, thunder can range from a sharp, loud crack to a long, low rumble (brontide).