The power of the mind is impressive, but the power of the soul within every creature, that's even more powerful if one learns how to harness and use it.

Soulsteal

Starting at 3rd level, each time you successfully deal sneak attack damage with an attack on a creature with an Intelligence score of at least 4 that is not a construct, an undead, an elemental, a plant or a fiend, you steal a portion of the target's soul, gaining a number of Soul Shards equal to the number of sneak attack dice you rolled.
You can have a maximum number of Soul Shards equal to half your WIS score. After each long rest, you retain half the amount of Soul Shards you had before the long rest, should you had only 1 Shard at the beginning of the long rest, you finish your rest with 0.

Soul Knife

Starting at 3rd level, as a bonus action in your turn, you can spend between 1 and 3 Soul Shards and create a blade of energy the length of a short sword.
The Soul Knife has the Finesse, Light and Thrown (40/80) qualities and you are automatically proficient with it. The Soul Knife has no weight and deals 1d6 Psychic damage per shard spent for its creation. Should you use the Soul Knife to perform a ranged attack, the blade will disappear after the attack is resolved.
The Soul Knife lasts for one minute, until you lose contact with it, you fall unconscious or die, and during this time you can decide to reduce its size so as to hide it inside your fist without it disappearing.
As long as it is active, you can extend the duration of your Soul Knife in subsequent turns by spending 1 additional Soul Shard as a reaction on your turn, making the blade last one additional round per Shard spent.

When you kill a creature capable for giving you Soul Shards using your Soul Knife, you gain a number of Soul Shards equal to the number of damage dice of the Soul Knife.

You can also decide to create two Soul Knife to be used one in each hand. In this case the maximum amount of Soul Shards you can use remains the same, but you divide the Soul Shards spent between the two Soul Knife to determine the damage of each.
They last an initial number of turns equal to twice your WIS modifier as a single blade, but the cost to increase their duration is separate for each Soul Knife.

Soul Restoration

Starting at 3rd level, as an action on your turn, you can spend 1 Soul Shard to make a dying creature within 10 feet of you that you can see stabilize and regain 1 Hit Point.

Vanishing Soul

Starting at 9th level, as an action in your turn, you can spend 3 Soul Shards to cast the one of the following spells on yourself:

• Invisibility
• Pass without Trace
• Spider Climb

Soul Render

Starting at 13th level, you improve your Soul Knife. When creating the blade you can decide to invest up to 5 Soul Shards, making the maximum damage the blade can deal up to 5d6.
Additionally, when you use your Soul Knife to perform a ranged attack, the blade reappears in your hand instead of disappearing after the attack.

Soul Savior

Starting at 13th level, you Soul Restoration feature can now be used on creatures you can see within 30 feet of you. Additionally, the maximum number of Soul Shards you can have becomes equal to your full WIS score.

Soul Reaver

Starting at 17th level, you learn how to use your own reserves of Soul Shards to rip the soul of your enemies to shreds.
As a bonus action on your turn, when you successfully perform a sneak attack on a non-construct target using your Soul Knife, you can decide to spend Soul Shards up to half your WIS score. The target has to make a CON saving throw against DC of 8+your WIS modifier+your proficiency bonus. On a failed save, the target suffers 3 levels of Exhaustion, while on a successful save it takes psychic damage equal to 1d8 per Soul Shards spent.
You can use this feature once every long rest.