Path of the raven

Willingly or not, the Shadowfell tainted you and the mysterious Raven Queen has sent to you a sinister envoy. 
As you walk by the side of destiny and death, in the form of a croaking companion, you may learn to use the feathered shadows to your advantage. 

The raven from beyond the veil

Mark of destiny

As a bonus action, you can mark a creature that you can see.
You always know the location of your mark, if you are on the same plane of existence. Your mark lasts until you dismiss it or until you use it to mark another creature.
A remove curse can remove it, however, the target first needs to succeed an 18 DC arcana check when it is applied, to know the mark properties.

Raven Queen's guidance

The Raven Queen offers her guidance to those who do her biddings.
When you chose this subclass, you gain proficiency in survival or investigation, to track down her foes.

Blurred shadows

At 9th level, you learn to blur yourself as does your raven, through your connection to the Shadowfell.
As an action, twice per day , you can veil yourself, giving disadvantage to attack rolls against you for the next minute.

Death's mercy

If death is already written upon your foes, at 13th level, you learn to seal their fate in a faster and more merciful way.
Once per turn, when using your sneak attack on an already wounded creature, you can use your reaction to add half your sneak attack dice as necrotic damage, rounded down.

Dark synergy

Your bond with your raven companion is stronger and can be used for strategic positioning.
At 17th level, you can sacrifice 30 ft of mouvement to switch place with your raven companion.