Definitions by Clear Quill

Nightmaring 

Nightmaring: Bottling up your rage/fear/sadness/regret/etc. to the point where you explode, doing something that you would never normally do.

Luna, in becoming Nightmare Moon, was one of the first recorded examples of Nightmaring

Nightmaring by Clear Quill August 6, 2011

Sparkling 

Sparkling: Unleashing a part of yourself that you normally keep contained

When the sonic rainboom reached Canterlot, Twilight started Sparkling.

Sparkling by Clear Quill August 6, 2011