Then, before you say another word, a body manifests for you, one of a female human. Your breasts are modest C cups, and you are average. "Ah!", says the ball, "I can already tell what you were born as."
All of a sudden, you gave off a gasp, as pain rushes through your legs. Watching them carefully, you cry out in sharp pain as they get pulled together, as if magnetised. Then they stuck together. Flesh began to grow, filling in the spaces between your former legs. Your pants seem to get ripped, as they suddenly fall in pieces around you. Soon, your legs have been replaced by a long limb. Then green sparkling scales begin to grow, running down the long limb. At the end, a sudden burst of pain races through you as two transparent fins push out the sides of the long tail.
Then your shirt seems to vanish, revealing your bra, which soon also vanishes. The C cups suddenly swell, growing incrementally larger, soon stopping at GG cups. Your areola seem to become larger, and a much deeper shade of brown. Then two seashells matilarize from nowhere, and cover your nipples, doing a fail job at a "bra".
Looking down, you find yourself unable to move, and you sigh. Suddenly the orb glows brightly, and when it stops, he has vanished, and you are now underwater!