@hotshot you can do it too if you have an eternity and 3 or more time pillars. The only thing stopping you is not having an eternity, which depending on your perspective may be a flaw. Just like magic, any seemingly absurdly powerful combination is fair.
If you want to theorycraft, the trainer's a good way to do it. It gives you access to every card, upped/unupped, but no multiplayer. www.elementsthegame.com/trainer.html
@willraven You can still get it with a high blacksmithing skill. You need to have many (preferable junk, so they cost less) items upgraded to high levels so they'll have only 30-40% chance to suceed, then pray for the best. The item doesn't have to be destroyed for it to count as fail; it just needs to not level up.
@RickyG18 - Crescendo Slash's problem is that it MUST be used consecutively, so you can't stop it and do something like using items or dieing. On the other hand, there's other ridiculous moves like Sin Strike or Money Attack!, which can (with farming) deal 9999 damage and carries over, or Fairy Dust which lowers both STR and SPR. There's a LOT of overpowered stuffs.