The Endersong

The endersong is a mob shaped similarly to a bird, but it is only found in the end atop sitting atop chorus fruit trees.

It is a hostile mob, and upon seeing a player, it shoots music notes at them. If these hit, the player takes 1 damage and is teleported a few blocks. Endersong can fly, so the only way to defeat them is with ranged attacks.

Upon defeat, an endersong will drop a random music disc and a new item called an ender harp.

Playing an ender harp will inspire allays to gather more items, allowing them to collect "partial" blocks (vines, flowers, slabs, but not things like wood or dirt), until running out of durability.

Crafting an ender harp with eight amethyst shards would make an amethyst harp. This would cause allays to duplicate when it is played, but does not extend their gathering abilities. This is the least durable harp.

Crafting an ender harp with four echo shards would create an echo harp. When played, this allows allays to gather any block with the hardness of wood or lower. Its durability is the highest of the harps.

(Note: these could be lutes if you want it to be more like Minecraft Legends. The echo kind could also be the legendary lute the player has there.)