Harbinger

Though your superiority in working through the shadows the shadows have given back. You have been gifted an ally from the the unknown that excels at hindering your opponents and distracting them.  

Shadow Ally

When you choose this archetype at 3rd level, you gain a familiar made of shadow taking the form of tour choice. During your turn, you may use a bonus action to have your ally use the help action for you or any other creature within 30 ft. of you.

 

Smokescreen

Starting at 3rd level, your Shadow Ally can be used to blind opponents. As a bonus action you can send your ally towards a creature which must make a dexterity saving throw. On a failure the creature is blinded for 1 minute or until it takes an action to disperse the shadow in it eyes. If the creature removes the shadow you still get to use your sneak attack against the creature as if you have advantage on the attack.

This action can be used a number of times equal to your proficiency modifier each day. These uses reset after a short rest.

Omen of Death

At 9th level, Your shadow ally has become much stronger. When you use your bonus action for the Shadow Ally feature and the creature you help makes an attack you can add 1d6 damage to the attack. you can use this a number of times equal to your level in rogue. these uses reset when you take a long rest.

 when you use your smokescreen feature you may instead target all creatures in a 10 ft. radius of a point within range.

Your ally can take the from of any medium creature, but looks to be made out out of shadow.

Walk in Shadow

Starting at 13th level, you can use a bonus action on your turn to gain advantage on the next Dexterity (stealth) check you make during the same turn.

you may also expend a use of smokescreen to give all creatures within 10ft of you advantage on the next Dexterity (stealth) check for the next 10 minutes.

Herald of Death

Beginning at 17th level, your Shadow Ally can become the living embodiment of death. After you have dealt damage to a creature you may use a bonus action to make a special attack. Your Shadow Ally swells to an enormous size and lunges at that creature Dealing your sneak attack damage on a hit using your DEX.

This feature can be used once per long rest, or be used again by expending three uses of smokescreen.