So from my research so far the only way i find this possible without playing the game for like 12 hours + would be ( due to the suggestion from pinkpajamas) Prinny throwing . Now the best way i can think of is abusing the hospital to get the muscles on top of that reincarnation using 200 bonus points on just health guarantees a health stat of at least 180,000 . The max health i've seen etna is 200K so in theory getting 2 ( 3 for safety because throwing prinnys does half their health in damage)getting the 2-3 prinnys to that point then on top of that possibly leveling them up a bit to down her. Estimated time for run is 4-6 hours . I will be running it for the first time here soon.