Ghost

Harnessing pure shadows originating on the Plane of Shadow, the Ghost laughs at those who think mighty walls and massive armies can prevent them from reaching their destination. Masters of this discipline have very likely spent significant time in the Shadowfell, learning to manipulate those energies in subtle ways. 

Armor Restriction

Shadow magic is notoriously difficult to use while wearing most armor. Features and abilities gained from the Ghost archetype are suppressed while wearing medium or heavy armor. 

Expertise

At 3rd level, choose two of your skill proficiencies. Double your proficiency bonus with those skills.

True Silence

At 3rd level, you've learned to harness shadows to absorb any sounds you might make. In areas of dim light or darkness, your movement no longer produces any sound unless you wish it to, including when climbing and swimming. Creatures that rely solely on sound to perceive treat you as being invisible in such conditions. In addition, you gain the ability to cast the Silence spell a number of times equal to your proficiency bonus. You regain all expended uses when you finish a long rest.

Shadow Haze

At 9th level you gain the ability to manipulate shadows to hide your true form, protecting you from harm. As a bonus action you can force shadows to cover your body, providing a bonus to your AC equal to your proficiency bonus until the start of your next turn. You can do this {{modifier:dex}} times, regaining all expended uses on a long rest. 

Friend of Shadows

At 13th level, wielding shadows becomes second nature. You can make Dexterity (Stealth) checks even when being observed, as long as you are within 30 feet of a shadow other than your own, and not in an area of sunlight. In addition, you gain the ability to cast Greater Invisibility once, and you must target yourself. You regain the ability to cast the spell in this way when you finish a long rest.

Ghostly Phase

At 17th level you gain the ability to step partially into the Shadowfell, creating portals that only you can see to move very short distances when necessary. You now ignore difficult terrain, and are able to pass through through any non-living material that is less than 5 feet thick. Your equipment and everything you are carrying phases with you. You cannot end your movement in an occupied space. If you do, you are shunted to the last unoccupied space you were in, taking 1d6 necrotic damage and becoming stunned until the end of your next turn. Walls of Force or similar magic prevents this movement. Spells and effects that prevent planar travel or teleportation also prevent the use of this ability.