Lightning-Make: Thor's Hammer

Lightning-Make: Thor's Hammer (雷光の造形魔法・卑劣王の槌 (ライトニング・メイク・トール・ハンマー), Raitoningu Meiku: Tōru Hanmā lit. Lightning Molding Magic: Hammer of the Vile King) is a Lightning-Make spell that calls down an enormous hammer from the heavens to pulverize everything in sight.

Description
When performing Thor's Hammer, the user condenses their magical energy into a solid, but rather unstable form, constantly exploding after a small amount of exertion—reducing the output of magical power from every particle, allowing the lightning to become stable and controlled through the guidance of the user. Once this is done, the user swipes both of their arms in a circular motion until the bottom of their hands meet. The hand on top has the index and middle fingers pointing upwards, while the other hand has the little and index fingers pointing downwards. As the user is making the appropriate gesture, their lightning is generated in front of them, before shooting to the skies, being molded into an enormous hammer which then slams down onto the area with amazing force, destroying everything within its hit radius sans the user themselves—however, it can also be concentrated in order to strike a single target out of others nearby. Because the lightning delivers a powerful blow that pulverizes everything in sight whenever it comes into contact with the opponent, to prevent constant and unnecessary catastrophe, Lightning-Make: Thor's Hammer's exterior is hardened and the eternano at its surface is cooled, tempering the exterior of the enormous hammer of thunder. However, Thor's Hammer does have a single weakness—its full power cannot be utilized inside a building. It is still overwhelming within a building, scattering all targets into dust, but the user must call forth lightning to utilize its full power.

Trivia

 * The spell's name and function is a reference to Thor's hammer in Norse mythology, Mjolnir.