Allay Duplicating only with a "favorite song".

The new dancing mechanic and duplication of the allay with an amethyst shard is great. However some might say it's too easy. To add a level of difficulty each Allay could have a "favorite song" where they can only duplicate if their favorite song is playing. This encourages players to seek out more allay or find all the discs to discover their Allay's favorite song and each music disk has an in-game purpose and a reason to collect them all besides just wanting to listen to them.