Spectral Gallop

Like the shadow horse you ride, you can temporarily phase yourself out of sync with reality, allowing you to pass through other creatures. You gain the following benefits.

Ability Score Increase. Increase one ability score by 1, to a maximum of 20.

Spectral Rider. When you Shadow Gallop, you and your mount can pass through the spaces of other creatures without treating them as Difficult Terrain. The first time each turn that you pass through each creature’s space, that creature must succeed on a Constitution saving throw (DC 8 plus your Proficiency Bonus and the modifier of the ability increased by this feat) or take Necrotic damage equal to your level.