Shadow Walker

Concealment

Starting at 3rd level, as a bonus action, you can turn invisible for a number of rounds equal to your Dexterity Modifier (min. 1) or until you hit with an attackl or force someone to make a saving throw. You can use this ability a number of times equal to your Dexterity modifier. You regain all expended uses back on a short or long rest. 

Back Stab

At 7th level when you hit with a weapon attack while under concealment the target must make a Constitution Saving Throw, DC equals 8 + Proficiency + Dexterity Modifier. On a failed save the target becomes stunned until the end of your next turn. 

Shadowy Movement 

Starting at 11th level, while you are in dim light or darker you can teleport to another space you can see within 120ft that is also in dim light or darkness. This uses up your movement. You can also do this as a Bonus Action. In addition, while you are in dim light or darkness, you have 120ft of darkvision.

Shadow Strike:

At 15th level when you make an attack roll while under the effects of your Concealment you can make a stealth check contested by the targets perception check. If you succeed you regain the expended use of Concealment and you deal an additional amount of damage equal to your Scout level.