After your Trial of the Nines, you gain the ability to manifest the old Heritage of devils. A set of wings, permanent in the Nine Hells, but harder to manifest in the Material Plane.

At Level 3, you can manifest your wings for an hour every Long Rest.

At Level 8, you have more control over your wings. You can manifest them an hour per short rest and dismiss them at will.

At Level 15, you have complete control of your wings in every planes of existence. You can manifest and dismiss them at will.