Shroudbearer

Shroudbearers are individuals that possess bizarre affinity with the Shadowfell, either by happenstance, ritual, or birthright, being able to channel and act as a living conduit for its essence. One of the more common manifestations of this is the ability to to project fragments of the plane's malign influence unto others. Upon finding purchase in their quarry, whispers cascade in the mind of their wielder: a vague static hiss of muted voices that soon escalate into psychic crescendo, telling him how he might best snuff out the life of his foe, regaling its weaknesses and vulnerabilities, bestowing fever visions of imminent mortality that all but guide the hand of his weapon to strike true. Some even possess the monstrous ability to take up the soul and guise of their victims, ensuring true death.

Death Shroud

Beginning at level 3, you can impose a damning curse upon a foe, laying bare its every weakness and vulnerability. As an action or bonus action, you can place a magical curse known as a shroud on a creature you can see that's within 60 feet of you, marking it as your shroud target. Creatures are unaware of your shrouds unless they can sense its magic. A creature may be subject to up to four of your shrouds at a time. Your shrouds last until you target another creature with this feature, the target dies, or the remove curse spell is cast upon the target. While your target has four shrouds, you know any damage vulnerabilities it has, and you can invoke your shrouds when you make a weapon attack against it (no action required). If you do, that attack as advantage, cannot have disadvantage, and if it hits, it critically hits and all of your shrouds on that target end after that attack resolves.

Step from Shadow

At level 3, you can emerge from the very shadow of those marked for death, beckoned by the magic of your shrouds. As a bonus action, you can magically teleport up to 15 feet for each of your shrouds on your shroud target to an unoccupied space that's adjacent to it.

Dead Ringer

At level 9, you gain the ability to take up the souls of your victims, granting the unsettling ability to assume their likeness. When your shroud target dies, you can choose to take its soul (if any). While its soul is in your possession, that creature can't be revived short of divine intervention or a wish spell. If you die, take another soul, the soul's body is revived, or release the soul as a bonus action , that soul is freed from your possession. Further, as an action, or immediately upon taking a creature's soul with this feature (no action required), you can magically transform your appearance to that of any creature whose soul you possess as per the Change Appearance effect of the alter self spell. A transformation made in this way lasts until you dismiss it as a bonus action or you transform again.

Reaper's Beckon

At level 13, no quarry can long elude you, the curse laid upon it calling to you incessantly, seeking out its bearer's death. You always know the direction and distance to your shroud target while it's on the same plane. You know your shroud target's exact location while it's within 120 feet of you. You can never be surprised by your shroud target, nor can it become hidden or invisible to you.

Soul Eater

At level 17, the influence of the Shadowfell has changed you into a monstrosity, granting you the ability to devour souls. Souls are no longer freed from your possession when you take another with your Dead Ringer feature. You can possess a number of souls at one time equal to your Rogue level. Further, you can exploit a soul you possess per the soul cage spell. A soul exploited this way is utterly consumed: you no longer possess it, and the creature it's from can no longer be revived even if you die, short of divine intervention or a wish spell.