Contains Hourglass expansion, which means Breast Expansion and Butt expansion, no sex, but has groping, and facesitting. This is my 2nd request, that will have three chapters.

Characters are Anthro.

When Twilight discovers a spell that can shrink and expand items, she decides to run a few tests first using potions. As she goes to grab an ingredient, Pinkie and Rainbow Dash decide to play a prank, that backfires at them.