Physician

Didn't care for the Way of Mercy monk, blending an eastern martial arts based fighter with a western plague doctor just feels weird. I can't get over the image of a plague doctor running sideways across a wall to punch someone to health out of my head. I feel like the rogue is a much better fit for a doctor archetype(i know, not exactly a new or groundbreaking idea), melding practiced knowledge with deft movements of the hands, so I tried my best to do that with this subclass. Any feedback on balance in welcome, especially the level placement of revivify. While 13 seems kind of high for a 3rd level healing spell, I decided on allowing its use without components similar to Alchemists ability to cast Lesser Restoration with their tools, as well as the fact that it is the same level that Arcane Tricksters would be getting their 3rd level spells as 1/3 casters. 

Tools of the Trade

When you choose this archetype at 3rd level, you gain proficiency with the Herbalist's Kit and the Medicine skill. If you are already proficient, you gain proficiency with another set of artisans tools or skill of your choice. Your proficiency bonus is doubled for any ability check you make that uses either of those proficiencies.

Hands of Remedy

You have become adept in the use of poultice and suture, able to heal the wounded as deftly as you deal death with a blade.  Starting at 3rd level, as an action, you can heal a creature for an amount equal to a roll of your Sneak Attack die + your wisdom modifier. You must have your Herbalist Kit on you to use this action. You can use this ability proficiency modifier times per day. You regain these uses at the end of a long rest. 

Contaminated Strike

Your familiarity with death and disease has taught you how to distill their very essence into your strikes. Starting at level 9, at the end of a long rest you can use your Herbalist Kit to coat one of your weapons with a vile contagion. Select a melee weapon with the finesse property, which deals piercing or slashing damage, or 20 pieces of ammunition that deal piercing damage. When you deal your Sneak Attack damage to a creature with this weapon or ammunition, the damage becomes necrotic. 

Last Ditch Effort

Starting at level 9, when you make a successful Medicine check to to stabilize a dying creature, you can apply your Hands of Remedy feature; doing so does not consume a charge of Hands of Remedy and can be used if all charges have already been spent. A creature can benefit from this feature once per long rest.

Resuscitation

You are no miracle worker, but Death will not have his prize without a fight.  Starting at level 13, using your Herbalist Kit, you can cast the Revivify without  material components. Once you use this feature, you can’t use it again until you finish a long rest.

Undeterred by Death

Having saved countless others from the brink of death, you have formulated a concoction of pain suppressants and restoratives to save your life in the most dire circumstances. Starting at level 17, upon receiving damage that would reduce your health to 0, but not kill you out right, you can use your reaction to instead drop to 1 hp instead and immediately use your Hands of Remedy feature on yourself. Once you use this feature, you can’t use it again until you finish a long rest.