Velma has a artifact in her possession, the Daemon Ritus (from the live action scooby doo movie)

This is the same artifact Scrappy used to become all powerful

she puts it on her chest, it shocks her a little, then thousands of ancient demon souls go inside the Daemon Ritus, she takes off her jacket, now in her white tank top

she's now beefed up, she has muscles that no girl can grow, they bulge a bit

Jinkies, those spooks are in for it now