Circle of Ink

Through rigorous study and lots of pain, those of the Circle of Ink can Tattoo any being that they have vanquished to their body and summon it to fight for them. The practice of doing so is brutal, but summons a being that acts separately with its own initiative and limited intelligence on behalf of the summoner.  

Ink Summoner

At level 2 when you choose this druid circle, when you do damage to a creature, and that creature dies, you gain the option to Tattoo this creature to your body over the course of your next long rest.  As an action, you can expend a use of Wild Shape to summon this tattoo into existence. It can look like the being it is based on, or stylized, based on how you tattooed it. This feature does not have the wild shape limitation of only being beasts. You can summon any being.

While the being is summoned, your maximum hit points are reduced by the hit points of the summoned being. You cannot summon beings with more hit points than you have. The summoned being persists for 1 hour or until released or killed. When the being is released (as a free action), the hour is up, or it dies, your hit point maximum increases to normal, but you regain only half of the hit points it reduced, rounded down. (A wolf would reduce max hit points by 11 and you would regain 5 hit points when you release it.) (May add a CR maximum here if the HP isn't enough, not sure)

You can still cast spells and concentrate on spells when the being is summoned. It acts as it's own entity. The summoned being acts immediately after you in the initiative order and follows your commands. If this being was a spellcaster in life, it can use only cantrips. If it has a weapon that uses ammunition, it magically never runs out. It does not inherit any  legendary or lair actions that it's living counterpart has. The being cannot communicate verbally or psychically, but can follow verbal or psychic commands. It knows nothing of it's former life, and so cannot make history checks or the like, but otherwise retains all saving throws and skills.

Circle of Ink

At level 3, You gain proficiency with disguise kits and forgery kits. If you utilize magical tattoos in your game, the DM decides weather this subclass gives you bonuses to those.

Sharing trauma

At level 6, As a reaction, when you or the summoned being take damage, you can choose which of you takes the damage.

Extreme Investiture

At level 10, You can choose to expend 2 uses of wild shape at once or 1 each on separate turns to summon 2 beings. The being with the lowest health pool only reduces your max HP by half of what it would if it was alone rounded down. (I.E. if you have a wolf with 11 hp and a giant rat with 7, the rat would take 3 hp. or with 2 wolves the 2nd wolf would take 5 hp.) 

Pain is an old friend

At level 14, when you roll below 10 on a concentration check on constitution saving throw, treat it as a 10. You also gain a +1 to your constitution modifier.