Rogue Poisoner/Alchemist

The Poisoner is a deadly class that focus' on using everything you can at your disposal. That includes your worst and most painfully toxic chemicals. How you came about these chemical? We wont ask, Feign Ignorance right? Anyway As you progress you will become more and more proficient with the knowledge of medicines, natural plants, venoms, and other such toxic concoctions. Your knowledge of how to use them will begin to grow as you learn more and you will be able to create more deadly toxins. Have fun murdering those nobles.

Chemical Experience

When you choose this archetype at 3rd level, you gain proficiency in the use of the Poisoner's kit and proficiency in the use of Alchemist's supplies. Also when using a poisoners kit, you may double your proficiency bonus.

Additionally, you gain advantage on any checks to identify poisons or potions. 

Poison Crafting

At 3rd level you gain the ability craft effective poisons (the exact selection is at the dm's discretion). If you create a poison that requires a save dc, that dc will be (8 + your prof. + your wis mod). All poisons you attempt to craft now cost only half the usual price and you only use half the materials.

Additionally, thanks to your extended amounts of time working with toxic chemicals, You now gain resistance to poison damage and have advantage on saves versus any poison effects.

Poison Immunity

At 9th level, You become immune to poison damage, poison effects, and are now immune to all diseases.

Alchemic Combat

At 13th level, you have advantage on all melee attacks against any creature that is Poisoned. The first melee attack of your turn that hits a poisoned creature is a critical hit if you are within 5 feet of the creature.

In addition, creatures that are surprised by you have disadvantage on saving throws against poison until the end of your turn.

Enhanced Alchemy

At 17th level, When you craft a poison or potion, you may now double the duration of the time you spend crafting the potion or poison and spend double the usual gold and materials to craft it. In doing so you may increase said potion or poisons efficiency in some way depending on whether it is a potion or a poison.

• If the potion or poison heals or does damage, then you may add your (wisdom modifier + your proficiency bonus + half your level rounded down) to that rolled number.
• If the poison or potion has a duration, then you may increase it's duration by half of its original duration. 
• Lastly if the Poison has a save dc, you may increase its potency by forcing the recipient of the poison to suffer disadvantage on their saving throw.