Nightmare Moon's eyes found Twilight. For a moment, the two only looked at each other. One breathing heavily, her body bruised and battered, her gaze narrow and determined. The other not breathing at all, a corpse split in two, black hollow sockets in her skull staring forward.
A blast streamed forward from Nightmare Moon's horn. A single torrent of energy, about as wide as a head, deep blue and black. Twilight didn't even try to intercept it, she knew she couldn't. Instead she dodged. She ran. To her side, as fast as her magic could make her legs move even at the cost of breaking their joints. Circling around Nightmare Moon, angling herself to get closer.
Nightmare Moon's spell followed her, fast enough to burn parts of her tail, leaving it smoking and corroded. The alicorn herself never turned, the beam firing from her horn did. All the while, black tendrils began to pour out of her gaping wound. They took hold of her lower body and her missing wing, and dragged them back towards her.
Twilight took notice of that, as she kept circling the other. She couldn't allow her to get to move again. If she got away, there might never again be a chance to do what she needed to. Once she was parallel to Nightmarish Moon's side again, once she saw her standing up fully and her wings spreading again, she knew she had to act. She took a violent turn, a sudden ninety degrees change in direction, and headed straight to the alicorn.
The spell hit her at first, leaving scorch marks over her coat where it did, but it was for a brief moment only. As she got closer, Nightmare Moon failed to adjust the angle of her blast quickly enough. In less than a second, Twilight was on her, and all her momentum left her body and was shoved into Nightmare Moon's. It left a hole in the side of her chest, a black stain of ichor on the ground on the other side of it. It pushed the alicorn slightly off balance, making her spell shoot high in the air, cleaving the skies and the storm around them.
Nightmare Moon turned slightly as she came down. Her spell ceased its flow, turned to a single point she slammed down to the ground in front of her. Twilight was already out of the way, already behind her. The teleportation, so close to the source of the disturbance, left her coughing out blood from her nose and mouth. It didn't matter. As a pillar of blue fire erupted where she'd stood and the ground cracked under Nightmare Moon's spell, she lit her horn again.
Nightmare Moon was quick to turn, ready to strike again. Twilight stood there. Twilight leaned closer, in the fractions of a second the events took place in. Her horn shone brighter and brighter, purple and gold. "Did you think I'd taken Celestia's magic just to fight you?" she asked, words carried out by her magic as pure meaning almost instantly transmitted. "I always knew I wasn't going to win that way. It was always about this."
Twilight leaned close enough to take hold of Nightmare Moon with her wings, and she almost did, feathers hovering mere millimetres away from the alicorn's skin. The light of her horn ballooned out, a sphere of gold that wrapped itself around both her and Nightmare Moon before the latter had time to strike. Then, the sphere collapsed on itself, and the two were gone.