Misaka Imouto's lightspeed lightning spear

The girl did not have time to be frozen in shock. She twisted her body and managed to roll a step away from the boy. She swung around her left hand as she could still move that one and gathered power there.

She released a lightning spear from it.

The spear of purple electricity moved forward at the speed of light and held enough destructive force to knock someone unconscious.

She did not think that it would act as a fatal blow.

As long as it distracted him long enough for her to get away, that was enough.

-Toaru Majutsu no Index (Old Testament) Vol 3, Ch 2