This story is a sequel to Rainbow Dash's Fishy Bud
Rarity receives a letter from an anonymous admirer... In a quarry. Rarity's curiosity gets the better of her, and indulges upon the letters request, however her assailant is not when she expects it to be. A six armed five eyed spider woman!
Coverpic I got from Deviant Art, here.
An Undertale and MLP smashup. Contains spider giggles, spider treats, and spider spiders