Ninja

The ancient arts of the Shinobi are usually passed down through generations, detailing the secrets how to become one with the shadows and hush around the battlefield like the shadow of a bird. Not many are trained in this way nowadays, but those who are are rumored to be as swift as an arrow, as silent as a cats paw and as deadly as an enraged dragon.

Nimble Fingers

Starting at 3rd level you gain proficiency with Poisoners kits. Also you can use the bonus action granted by your Cunning Action to use an Object.

Distracting Maneuver

Also at 3rd level you may attempt to distract your foe by throwing something at it (e.g. Sand, dirt, etc). As a bonus action the target must succeed on a CON saving throw (DC = 8 + DEX + PB) or be blinded until the start of your next turn. You may use this feature a number of times equal to your PB and regaining all expended uses after taking a long rest.

Bleeding Strikes

Starting at 9th level, once per turn, when you hit a creature with a melee weapon attack you may force it to make a CON save (DC = 8 + DEX + PB). On a fail the creature is bleeding and takes 2d4 bleeding damage at the start of its turn until the wound has either be treated medically or a spell restores more than 15 HP at once. If you scored a critical hit the target has disadvantage on this save. Undead and constructs are unaffected by this feature.
This bleeding damage increases to 3d4 at 14th level and to 4d4 at 18th level.

Shadow Step

At 13th level you gain the ability to become one with the shadow cloaking the battlefield. When you are in dim light or darkness you may use your bonus action to teleport up to 30 feet without making a sound. You may do so once before needing to complete a short rest.
At 18th level you may use this feature twice instead of once per short rest.

Ninjutsu

At 17th level you finally understand the deepest secrets of your teachings, allowing you to command the elements using an assortment of hand signs. You gain the ability to cast the following spells at 3rd level: Fireball, Haste, Lightning Bolt, Sleet Storm. You may do so once per short rest. Your casting ability for these spells is Dexterity.
Once you reach 20th level you may cast these spells at 5th level instead.