In Scuttle Town, go to the Shop and Purchase "Pike Ball"
for 50 gems
Head to Pumpkin Fields and go to the right pass the travel point and kill the enemies that spawn endlessly, as they will occasionally drop magic for you to keep your Pike Ball Active.
It is worth nothing, I had The Magic Regen Book. However with rapid succession of killing the enemies that never stop spawning you should be able to net this achievement with no problem
Location (Right hand side)https://vignette.wikia.nocookie.net/shantae/images/e/ef/RR-B...