Ninja of the Smog

In the halls of Bast, hidden in the northernmost regions of the Gaping Maw, lies a temple dedicated to the Mistress of the Shadows. These halls are the location of the legendary clan of Pirate Ninjas, a somewhat silly-sounding group of marauders who specialize in stealth and the world's various elements. In the land of Einess,  they are known as the reapers of the high seas, slaughtering entire ships with nothing but 3 honed clansmen and a small, camouflaged rowboat. Victorious assassinations usually mean that the ship you worked so hard on getting will be sold or dismantled for parts.
Of the various ninjas, the Ninja of the Smog is the ninja who specializes in poison and playing with toxic materials. They gain proficiency in poisoner kits early on and can get a discount when crafting poisons. At later levels, the ability they have to fight with poisoned weapons increases, giving them the upper hand in combat. Once they have mastered their respective elements, the Ninja of the Smog fully controls their own techniques, allowing them to become the very element they control.

***In order to maximize effectiveness, it is recommended to take the Poisoner Feat from Tasha's Cauldron of everything, to increase the number of enemies your poison can affect.

Sweet Serums

Starting at 3rd level, your years of dedicated training are starting to pay off. You gain proficiency with the Poisoner kit and have the ability to craft poisons with cheaper materials. You are able to craft poisons worth up to 300 gold's worth of materials at half price. The maximum amount increases to 600 at 7th level, 1000 at 11th level, and 1500 at 15th level.

In addition, repeatedly subjecting yourself to your own materials has given you resistance to Poison. You are now resistant to poison damage and have advantage on saving throws against being poisoned.

Poison Craft

Starting at 3rd level, your years of dedicated training are starting to pay off. You gain proficiency with the Poisoner kit and have the ability to craft poisons with cheaper materials. You are able to craft poisons worth up to 300 gold's worth of materials at half price. The maximum amount increases to 600 at 7th level, 1000 at 11th level, and 1500 at 15th level.

Toxic Touch

When you choose this archetype at 3rd level, you gain the ability to cast the cantrip Poison Spray at will. If you already know the spell Poison Spray, then the range of Poison Spray increases to 30 feet. Spell save DC is 8 + spellcasting modifier (INT) + proficiency bonus.

Venom Shock

Starting at 9th level, when you perform a sneak attack with a dagger, you can attempt to stun a foe instead of inflicting the poison's effects. Target must make a Con save against your Spell Save DC. If failed, your target is stunned until the end of their next turn.

In addition, you are able to perform sneak attacks with your Poison Spray attack. A target has to make the saving throw based on your spell save DC, and if they fail, they take the poison damage, as well as your sneak attack damage. If they succeed, it is considered a missed attack, and the target is aware something tried to attack them.

Smog of War

By 13th level, you have learned enough about your element to gain a limited amount of control. You are able to cast the spell Misty Step an equal number of times as your proficiency bonus per long rest. When you cast this spell, you can choose to make everyone within 5 feet roll a Constitution saving throw equal to your Poison Spray DC. If failed, they take 8d8 poison damage, and are given the Poisoned condition.

Additionally, when you kill an enemy with a Sneak Attack using a poisoned or poison-enchanted dagger, you can use your reaction to inject a foe with your dagger's poison, and push them up to 20 feet away. After they stop moving, they explode in a poisonous cloud. All creatures within  must make a DC 17 Dex saving throw or take damage your Poison Spray damage.

Master of Smog

When you reach 17th level, you have become a true master of the Smog. You are capable of casting the spell Gaseous Form an equal amount of times to your proficiency modifier per long rest. In addition to the effects of the spell, if you and another creature are in the same space at the start of their turn, the creature must make a DC 20 Constitution saving throw, or take 12d10 poison damage and be inflicted with the Poisoned status. Making the save deals half the total damage, and they are not considered poisoned. Creatures that do not need to breathe do not take any damage from this ability.

In addition, your body's energies attune to your element, turning your very blood into poison. You are immune to poison damage. Healing spells and healing potions no longer have an effect on you, but if you are struck by, injected, consume, or are affected by poisonous magical attacks above the 1st level spell slot, you can absorb the attack and heal an equal amount to the damage you were supposed to take.

Poison Heal

When you reach 17th level, If you are struck by, injected, or consume poison attacks created or used by others, you can absorb the attack and heal an equal amount to the damage you were supposed to take.