Thunderstorm (サンダーストーム Sandāsutōmu) is a technique introduced in Kingdom Hearts Birth by Sleep. It allows the user to launch small salvos of electrical bursts at targets.
Mechanics
In Kingdom Hearts Birth by Sleep, Thunderstorm is a Shotlock that has a maximum level of 4 and max lock of 5. After the initial volley, the player can perform extra attacks by pressing 
at a specific time to fire additional blasts. The more accurate the player's button press, the more bursts will be fired.
In Kingdom Hearts 3D: Dream Drop Distance, Thunderstorm is a Link Style used by Riku. While activated, Riku will be able to string together combo's consisting of him spinning and dashing towards the enemy. He starts his combo by normally attacking the enemy, then he spins, dashes, fires thunder shots, and his finisher has him surging at the enemy at high speeds.
In Kingdom Hearts Union χ, Thunderstorm is a special attack that targets all enemies. It costs 4 special attack gauges to perform.
Learning Thunderstorm
Kingdom Hearts Birth by Sleep
- Terra obtains Thunderstorm from a chest in The Chateau.
- Ventus obtains Thunderstorm from a chest in the Mousehole.
- Aqua obtains Thunderstorm from a chest in the Foyer.
Kingdom Hearts 3D: Dream Drop Distance
- Riku can use Thunderstorm by linking with a Thunder-style Dream Eater.
Kingdom Hearts Union χ
- Thunderstorm +5 is the special attack for medal 997: Key Art 16 (EX+).