Cosmic Wings (Princess Lillian in Whimsy dale) requires rainbow goblin to open portal. Green Leather Wings - Reward in Diablo 3 RoS for completing all the Master Set Dungeon Achievements/Goals. Only one set of Wings can be used at a time 7. When obtained, they can be added to the Wardrobe. When used, they apply or remove a pair of butterfly wings with deep reflection of a cosmic sky.
They drop from Princess Lilian in Whimsydale (not in Whimsyshire). The easiest and safest way would be to buy them on Odealo market from professional boosters Cosmic Wings are a vanity item for Diablo III, added in patch 2.4.1. Their rarity, however, makes them nearly impossible to obtain for casual players. Cosmic Wings and Wings of Mastery are the coolest cosmetic items in Diablo 3.
