Ghost, Variant (5e Subclass)
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Some rogues enhance their fine-honed skills of stealth and agility with the magic of the Ethereal Plane. These rogues include highly specialized assassins, spies, and thieves for hire and those already in the service of a government or large organization. Undectable, untouchable and notoriously difficult to prepare against, ghosts are exactly what they claim to be.
I make this change to nerfed a little and make more likely to a DM let you play this. Please check the original version.
Starting at 3rd level, when you use the bonus action granted by your Cunning Action to take the Phase action. When you do so you become semitransparent, you can move through non-magical difficult terrain without expanding any additional movement, and can move through non-magical objects and creatures. If you end your turn inside an object or creature, you are immediately shunted to the nearest unoccupied space that you can occupy and take force damage equal to the number of feet you are moved. You can use this feature a number of times equal to your Int plus your Proficiency bonus per long rest.
Also at 9th level, you can now Phase through magical terrain, objects and creatures without issue such as those produced by hallucinatory terrain or a Leomund’s tiny hut but not those which extend into the Ethereal Plane such as a wall of force. Additionally you gain advantage in the next two melle attacks you do if you already haven´t.
By 13th level, you've displaced yourself so many times that you've developed an otherworldly sense. You can see into the Ethereal Plane when you are on the Material Plane, and vice versa. In addition, when you gain blindsight it becomes up to 30 feets.
Begining at 17th level, you've mastered your ability to Phase. When you Phase, you completely disappear into the Ethereal Plane becoming invisible and unable to produce sound. You can keep this form for a number of rounds equal to your Int plus your Proficiency bonus and it ends early if you fall unconscious.