Ancient Symbiosis

Far in the past was a civilisation long forgotten, and instead using physical tools, each person of each profession had an artificially made symbiotic creature made of a liquid living metal that can harden and expand on command.
You are infected with one of these symbiotes, though diminished and damaged from age. To recover it's memories and strength, you must let it consume the flesh and blood of thinking beings. Do this for it, and you have a faithful companion and weapon at your service.

Symbiote Transformation

Also at 3rd level, your symbiote learns to envelop your body in tendrils of liquid metal, hardening in to armor and it's signature "tool".
As a bonus action, you transform into a special hybrid form for up to 1 minute, which resets with each successful hit. During this period, you are primarily controlled by your symbiote and have limited control. While you an make actions and bonus actions as you see fit, to speak as yourself, you need to make a wisdom saving throw, and succeed a 8 DC roll. If failed, you will have to convince your symbiote (personality controlled by DM) to share your message with your party.
You can use a bonus action to retract your tool and armor, and you automatically revert to your normal form if you fall unconscious or die.

 

Your symbiote is, primarily, a tool. The armor functions as protection while using the tool, but the weapon that is made as you transform is the purpose for the symbiote.

Thus, you can choose a single simple or martial weapon as your symbiote tool that appears with your symbiote form. You a proficient in this weapon.

If you've consumed 5 bodies by the time you reach level 5, you may upgrade your symbiote tool to a +1 version of that weapon. At level 11, and if you've consumed 15 bodies, you may upgrade to a +2 version of that weapon, and if you consume 20 bodies by the time you reach level 18, you may upgrade to a +3 weapon. 

Despite being a +1 weapon at level 5, it will not count as magical.

 

You can transform a select amount of times per level.

Level			Transformations
1st			2
2nd			2
3rd			3
4th			3
5th			3
6th			4
7th			4
8th			4
9th			4
10th			4
11th			4
12th			5
13th			5
14th			5
15th			5
16th			5
17th			6
18th			Unlimited

Symbiote Form

Selecting this option has updated the character sheet with the features of your Symbiote Form.

Ravenous Evolution

Your symbiote, while damaged, can regain it's strength through consumption of thinking things in your transformed form by opening up your abdomen like a massive maw, and use tendrils to draw a body inside to be consumed.
It is weak now, but will grow with strength... But it must feed.

Out of combat, you are able to consume the bodies of any creature capable of speech. The body needs to either be alive (at 1 hp and/or unconscious), or within 5 minutes after death.
Consuming a thinking beings will let your symbiote heal your body, giving you healing equal to your one hit die + your Constitution modifier. You can heal this way once per short rest, and you can consume a maximum of 3 bodies per long rest.

If you've consumed 5 bodies by the time you reach level 5, you may upgrade your symbiote tool to a +1 version of that weapon. At level 11, and if you've consumed 15 bodies, you may upgrade to a +2 version of that weapon, and if you consume 20 bodies by the time you reach level 18, you may upgrade to a +3 weapon. 

Additionally, at level 10 you get the ability to consume enemies who are dead or unconscious in combat as an action, and at level 15 you can do it as a bonus action. You may also heal twice per short rest this way at level 10, and thrice at level 15.

Symbiote Transformation Features

While you are transformed, you gain the following benefits and drawbacks:

Symbiote Strength. You have advantage on Strength checks and Strength saving throws, and you have a +1 bonus to melee damage rolls. 

Liquid Metal Armor. You have resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks. Additionally, armor worn is nullified and replaced with an AC of 14 + Dexterity score.

Pull and Release. You can apply your Crimson Rite feature to your symbiote tool to bind it to the symbiote's armor. When thrown, the weapon is attached to the armor with a tendril, and can be pulled back easily. While active, you can roll hemocraft die again to pull enemy to you (Enemy needs to make your Hemocraft DC Strength Save if Medium size, automatic failure for larger than Medium), or pull yourself towards the enemy (only on larger than medium enemies, and needs to succeed an Athletics roll matching your Hemocraft DC) if you successfully strike an enemy with the thrown weapon.

Bloodlust. If you start your turn with fewer hit points than half your hit point maximum, you must succeed on a DC 8 Wisdom saving throw or move directly toward the nearest creature and use the Attack action against that creature. If you’re concentrating on a spell or are under an effect that prevents you from concentrating (such as the barbarian’s Rage feature), you automatically fail this saving throw.

If you have your Extra Attack feature, you can choose whether to use it for this frenzied attack. If more than one creature is equally near to you, roll randomly to determine your target. Once your attack is resolved, you regain control of yourself.

Liquid Metal Armor

You have resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks. Additionally, armor worn is nullified and replaced with an AC of 14 + Dexterity score.

Symbiote Strength

You have advantage on Strength checks and Strength saving throws.

Memories Awaken

At 7th level, your symbiote's memories of the past are starting to reform, giving it access to further power from the past.

Your symbiote tool from now on count as magical for the purpose of overcoming resistance and immunity to non-magical attacks and damage.

You can now also understand, read and write in Primordial while transformed.

Advanced Transformation

At 11th level, symbiote integrates completely with your circulatory and nervous systems, transforming your Blood Curse into a shared assault. You gain the following benefits:

Bonded Regeneration. At the start of each of your turns when you have at least 1 hit point but fewer hit points than half your hit point maximum, you gain hit points equal to 1 + your Constitution modifier (minimum of 1). If you are in symbiote form, you gain these hit points before you must make the saving throw for your bloodlust.

Symbiotic Brand. When you hit a creature with a weapon augmented by your Crimson Rite your symbiote leaves a trace of itself behind. The target takes extra damage equal to your hemocraft die at the start of each of its turns. This effect lasts until the brand ends or you choose a new target.

Reactive Tendrils. When a creature within 10 feet of you makes an attack against a target other than you, you can use your Reaction to lash out with a parasitic tendril. Make a melee weapon attack. If it hits, the target takes your Crimson Rite damage and must succeed on a Strength saving throw against your Hemocraft DC or be pulled 5 feet toward you, disrupting their momentum.

Bonded Regeneration

At the start of each of your turns when you have at least 1 hit point but fewer hit points than half your hit point maximum, you gain hit points equal to 1 + your Constitution modifier (minimum of 1). If you are in hybrid form, you gain these hit points before you must make the saving throw for your bloodlust.

Brand of the Voracious

Starting at 15th level, you have advantage on the saving throw for your bloodlust while in hybrid form. Additionally, your Brand of Castigation can now bind a foe to your symbiote's ferocity. While in your symbiote form, you have advantage on attack rolls against a creature branded by you by either Brand of Castigation or Symbiote Brand.

Symbiote Transformation Mastery

At 18th level, you have achieved perfect symbiosis. You and your partner has surpassed it's original purpose, and is now can achieve it's untapped potential.
Your can use your Symbiote Transformation feature an unlimited number of times, and your hybrid form lasts until you revert to your normal form, fall unconscious, or die.

Additionally, when a Crimson Rite is active while you are in your symbiote form, you have increased reach of 5 feet, gain the ability to create wings as a bonus action, giving you a flying speed equal to your walking speed for 1 minute, or create gills and fins, giving you a swimming speed equal to your walking speed and the ability to breathe under water for 1 minute. You can do one of these transformations per short rest.

You also gain the Blood Curse of the Howl for your Blood Maledict feature. This doesn’t count against your number of blood curses known.