Mjölnir

Mjolnir: is the hammer of the thunder god, Thor, utilized by Beatrice Flowerchild through the Berserker Class Card. It is a massive, ornate hammer that requires a massive arm of great strength in order to wield. It is a powerful weapon, and it can be thrown with great force. It uses the power of lightning in order to attack once activated as a Noble Phantasm, but its full power cannot be utilized inside a building. It is still overwhelming in such a state, scattering all targets into elemental dust, but it must call forth lighting to utilize its full power.

Raising towards the sky outside causes lighting to strike it, doubling its potential power. If more lighting is called forth, it increases even more in power, changing its shape as it takes in the lightning.