As your Humonculus body adapts and blends with the Vampiric DNA of your donor your blood mutates, making your psychic powers more volatile, but far more potent.
Passive traits:
Vampiric Transformation : You are Able to Transform into a Creature of the night, that from the material plane, and below CR 3
Supernatural speed, you climb and walking speed is set to 50ft and gain a flying speed of 10 foot
KOWA'S GIFT : at the end of your turn you can roll 2 of your hit die and you heal the result plus your Constitution modifier.
Blood Frenzy: When below half hitpoints you enter a blood frenzy state, your strength, dexterity and constitution score is set to 23 and gain all the benefits of the scores for 10 minutes. However you must use one of your actions to perform an unarmed attack (bite) as a bonus action on the closest living creature at the end of your turn, if you fail to do the bite action your strength, Dex and Con score's are set at 8 for the remainder of the 10 minutes.
Apex Ability: Fukutsu no ketsui (1 charge)
You activate this charge with a free action, for 1 minute you have resistance to 1 damage type of your choice, your sneak attack die become a d8, gain a +1 to hit for all attacks.
You choose one hostile creature within 120ft of sight, that creature's attacks against you have disadvantage.