Specter, fixed

Some rogues just don't like the odds that come with being stuck on the material plane, while others find solace in the Ethereal Plane. These rogues learn how to harness the magic behind plane-shifting spells to hop between the Ethereal and Material Planes. Some are spies, others are thieves, the rest assassins. There is a rumor that the first specters were taught by a gnomish thief by the name of Noxtrim. The results are the same: you don't want these rogues to be the ones after you; they might just come out of nowhere.

Phase Strike

At 3rd Level, the specter gains the ability to surpass physical defenses. When you make a sneak attack, your damage is now psychic damage instead of piercing. 

Ethereal Movement

At 3rd level, your cunning actions have additional effects:

• When you use your Dash action, you phase in and out of reality, allowing you to ignore difficult terrain. This also allows you to move through objects that are less than 5 ft thick as well as creatures. If you end your turn in an object, you are immediately forced out, taking 2d6 bludgeoning damage. Because you're not completely incorporeal, if you move past a creature that is considered an enemy and you leave their reach, you still take an opportunity attack although they have disadvantage to hit you.  
• Your disengage action is replaced with a blink action. This isn't the spell, rather an ability that mimics the spell. You are still restricted by your movement as to how far you can travel in a blink. You are able to blink to a spot up to half your movement away that you can see. You may use this ability before, after, or during your movement.
• When you use your Hide, if you have used either your dash or blink and you end your movement in a spot with at least 50% cover, you gain advantage on your stealth check.

Eyes of the Ethereal

At 9th level, you can now change the composition of your eyes. In doing so, they become blank and pale. You can use this twice before a long rest. When you activate this feature as an action, you gain the following benefits:

• You can see invisible objects and creatures up to 15 ft. from you. 
• You can see into the Ethereal Realm while on the Material plane and visa versa.
• You gain blindsight up to 15 feet away.

This lasts for a number of rounds equal to your Intelligence modifier, after which you must finish a short or long rest before using it again. 

Walk the Ethereal

At 13th level, you can now fully phase into the Ethereal plane for a short time. As an action, you phase your body, vanishing from sight. While on the Ethereal Plane, you can only affect and be affected by other creatures on that plane. Creatures that aren't on the Ethereal Plane can't perceive you and can't interact with you, unless a special ability or magic has given them the ability to do so. You can only spend a number of rounds up to your constitution modifier there before you are ejected from the Plane. You are ejected from the plane at the end of your turn. When you leave the plane willingly, you use a bonus action to do so. 

You can use this ability once per long rest. 

Specter's Strike

At 17th level, you can now attack with deadly vengeance. When you attack, you can make a target make a Constitution save DC equal to 8 plus your proficiency bonus plus your Intelligence modifier. On a failed save, any damage they took reduces their maximum health by an amount equal to your rogue level times your Intelligence modifier. The health returns after a long rest. 

Recharge 6: You may not use this ability again until you roll a 6 on a d6. This is rolled at the beginning of your turn.