This Blood Hunter Order is inspired by Chara from Undertale and XChara from Xtale.

A Soul---3rd level

 

Starting at 3rd level, whenever you see a creature drop to 0 hp, you can use your reaction to collect its soul. The creature makes a Charisma saving throw against a DC equal to 8 + your Prof. Bonus and Int mod. If the creature fails, you collect its soul, if success, you don't, and cannot collect its soul again for 24 hours. There is a limit of how many souls you can collect, which the maximum is equal to your level + your Prof. Bonus/your Int mod, but at 20th level,  this limit changes to unlimited. Using your collected souls is rather harsh and painful to the souls as you destroy the wrath of every soul for your body. In addition, you can see any creature's soul if within 15 feet of you.

 

A Soul---3rd level(continued)

These uses are described as seen below:

-ADJUSTMENTS: you can destroy one soul to reroll damage, checks, saving throws, and Attack rolls, but you must use the new roll

-HARM: As a bonus action, you choose a creature within 120 feet of you, the creature must succeed a Charisma/Dexterity saving throw or take 2d8 necrotic damage per soul used, destroying each soul you use.

-HEAL: As an action, you destroy as many souls as you want (a maximum of your Prof. Bonus), regaining hp equal to the number of souls you consumed times your level divided by 3, rounded down, plus your Int mod/Prof. Bonus, minus each soul's highest Ability Score Mod. 

 

Steal Soul---7th level

Choose a creature within 120 feet of you, the creature must make a Dexterity saving throw (the creature can choose to fail) against a DC of 8 + your prof. bonus + your Int mod/Str Mod/ Dex Mod. if the creature fails, the creature is restrained and moved 30 feet in any direction (like in air) or absorbed 2d6 bludgeoning damage. While the creature is in this way, you can move it 30 feet as a bonus action or 45 feet as an action, or crush its soul, dealing 4d6 bludgeoning damage as an action. You can dismiss this effect (but the creature will fall, and this requires no action). You can have up to only your prof. bonus/your Int mod creatures tortured in this way, it can't exceed your maximum. You can attempt to steal the creature's soul too, forcing the creature a Charisma saving throw against the same DC, on a failure, the creature is moved toward your collection of souls. In addition, you can mix a soul you have with your own, your appearance changes logically, and you can switch your traits, features, ability scores, etc, as long as your character is not too overpowered, and is a little balanced. As, an action, if you mix you character with a creature's soul you collect, your hit point maximum can change, equaling half your hp maximum + the soul's hp maximum, though your current hit point maximum remains the same, if it exceeds your new hp maximum, it equals your new hp maximum instead. The soul is occupied by you. If you want to remove the soul out of your collection or with your soul, you choose a spot within 60 feet of you that is unoccupied, the creature's body lays there and if it was dropped to 0 hp, it is stable now with 1 hp . If it was stolen, it remains with its current hp and becomes active. If the creature's soul was mixed with yours, you become the soul which before you were mixed with the soul. Once you steal a creature's soul, you can't do so again until you finish a long rest, at 20th level, you can steal an unlimited number of souls.

Corruption Velocity---11th level

Your Dark Velocity feature's speed boost increases by an additional 10 feet, and you deal an extra 1d8 necrotic damage  in addition to the speed boost.

Control Soul---15th level

Starting at 15th level, the inner darkness of yourself mastered the ways of how he/she can summon souls and possess them. You summon one of your souls in an unoccupied space within 30 feet of you, the soul appears and takes its own initiative, you control the soul on its turn. You can have only a number of souls summoned equal to your level divided by 3, halved. When you feel to, you can desummon the soul(s)(requiring no action), but the souls must be out of your collection (see Steal Soul feature).

Cloak of Vanish---18th level

You gain these features as shown below:

-You are invisible unless you attack or move. You become invisible if you stay still for one other creature's turn.

-When you are making death saving throws, you can destroy one soul to reroll it, but you must use the new roll.

-You gain a flying speed of 30 feet, and can use this for only 1 minute. You can use this 3 times, but must finish a long rest to regain all uses.