Incorporeal Horseman

mounting or dismounting a creature costs you only 5 feet of movement, rather than half your speed.

as an action when you are riding your Phantom Steed; you, your Phantom Steed, and Anything you both are wearing or carrying become Incorporeal until the start of your next turn. While Incorporeal the you both gains Resistance to Bludgeoning, Piercing, and Slashing from nonmagical attacks and Vulnerability to radiant damage and can move through other creatures and objects as if they were difficult terrain. You both takes 1d10 force damage if one of you ends your turn inside an object. You can use this feature three times, and You regain any expended uses when you finish a short or long rest.