Updated: Jul 20, 2019
When in battle, a coin from the Demon, Lady Luck, is present, and will be used to flip for a chance to hit with some attacks. This is usually reserved for moves that have an immense pay off if they do hit. The coin is represented by Lady Luck herself, and has her head and tail on the coin.
Here's a look at flipping the coin in battle:
In the episode The Swirling Vortex, there's a way to unlock Lady Luck herself. Having her in your collection can make her a great asset. With Lady Luck present, she controls the fate of the coin, causing your coin flips to always land on heads, and the opponent's will always land on tails!
In addition to this, she has a 50% chance with her attacks to 'critically hit', making her attacks deal effective damage, even when she is not dealing a weakness!
Lady Luck's unlocking quest is quite involved, so it's only right when you unlock her, she should feel powerful. We can't wait for you guys to find her!