The Barber wants to remember how to create the ideal green hair dye. He believes the key to the perfect shade lies in the duality of the color itself. It needs to be both fresh and natural as well as mysterious. The Barber asked you to speak to someone who would know more about the mysterious aspects of green, those being envy and immortality.

The Collector mentioned that the Ectoplasm Shards inside the Nomad Highlands Hollow Hall have the perfect color and qualities for creating a mysterious green. The Collector can craft a key to open the Hall for you only once you've passed through previous Halls. Gather Ectoplasm Shards in the Nomad Highlands Hollow Hall and return to the Barber with them in your inventory!