Rainbow Dash is bored. Twilight won't stop doing paperwork, even though she promised her that they'd go flying together. Bored, testy, and at least somewhat curious, she asks Twilight what, exactly, is so important.

Upon discovering the potentially sexy nature of the "biological modification" spell that Twilight is evaluating, Rainbow humbly requests that Twilight test it.

On her.

Contains: Futa, large/hyper cocks+balls, futa on female/futa on futa, excessive cum, bukkake, frottage, blowjobs, large insertions/vaginal sex, stomach bulges, dominance/submission, and (implied) impregnation. Inspired by an RP with Khylo. Coverart by kattritaja.