Heir of the unseen Hunter

You uncovered the secret recipees and formulas to synthesize your own Poisons, as did the unseen Hunters before you.
With their knowledge you now start your journey to claim their heritage and your future. The Unseen Hunters were a secretive society, only trading knowledge with their pupils.
Your repertoir in the crafting and usage of Poisons increases trenemdously as you walk their path. But now it is time to write your own story with their forgotten secrets.

Multipurpose Poison

If by Chance or by Fate, you learned how to concoct your own special made Poison like the unseen Hunters themselfes, to serve you in any situation. 
Starting at Level 3 you create a Poison dosage using your Bonus Action, up to an amount equal to your Proficieny Bonus times per Long Rest.

Choose one of the following effects each time you create one. Their  DC 8+ Proficiency Bonus + Dexterity Mod.:

• Force the target to make a Con Save, on a failed save it takes an amount of damage equal to 2d8, half on success. You can choose between poison, necrotic, acid, or fire. The damage increases to 3d8 at level 5, 4d8 at level 9, 5d8 at level 13 and 6d10 at level 17 in this subclass.
  
  
• You force the target to make a saving throw for one of the following conditions.
  blinded - Con, frightened -Wis, poisoned - Con

And choose one type of delivery your poison takes:

• contact duration of 1minute, with a save at the end of each of their turns.
• injury duration of 1minute, with a save at the end of each of their turns. You can coat your weapon as part of the attack action used to attack.
• inhaled duration of 1minute, with a save at the end of each of their turns.
• ingested duration of 10 minutes, with a save at the end of each minute

Adjusted Formulas

Starting also at Level 3, you now can increase the potency of other poisons you use, albeit a limited amount.
You can increase the DC of other types of poisons you use to your Multipurpose Poison DC, requiring no action. You can use this feature a number equal to your Dexterity Modifier per long Rest.

Poison conditioning

Also starting at Level 3, your knowledge on how to hand poisons increases.You are now more resistant to them.
You gain resistance against poison damage and have advantage in saving throws against Poisons and the Poisoned condition..

Supreme Poisons

Starting at level 9, you delved deeper into the arts of Poisons than before. The usage limit of your Poison creation is now increased to 1.5 times your proficiency Bonus (rounded up).
And you gain access to new conditions for them.

silenced - Int, incapacitaded - Con, and for ingested only, sleep - Wis

Seeking Venom

Starting at level 13, you can sneak attack enemies without advantage, as long as they have failed a saving throw within the last turn against one of your poisons.
Enemies hit by your sneak attack now have disadvantage against your poisons till the end of your next turn.

Master Poisoner

Starting at lv 17, your poison mastery reached a new peak. The Damage of your Multipurpose Poison now used a d10 for its damage and the limit of uses per Long Rest increases to twice your proficiency Bonus. Additionally they gain a new Bonus depending on their type as follow:

• Ingested: A condition applied by these now lasts for 1 hour, with a repeated saving throw every 5 minutes instead.
• Inhaled:: The covered area increases to a 10ft. Cube.
• Contact: On contact with an enemy, they now decrease their AC by 2 for as long as the effect lasts, minimum of 1 round.
• Injury: This type can now coat up to two Weapons or Projectiles per dosage with the same action.