Underground Surgeon

After years of providing illegal medical services to bandits and people in the slums with little resources, you learned how to use your medical knowledge to protect yourself against danger. Underground Surgeons are masters at analyzing and exploiting weak points, as well as keeping their allies alive.

Siphon

When you choose this archetype at 3rd level, you can expend your life force in order to use certain abilities. You have a pool of Vitals equal to your rogue level x 10 which replenishes after a long rest.

Combat Medic

Starting at 3rd level, you gain proficiency in the Medicine or Perception skill if you don't already have it. As a bonus action, you can spend 10 Vitals to heal a creature within 5ft for 1d6 + your Wisdom modifier. Additionally, if a non-hostile creature is injured within 60ft from you that you can see, you gain an additional 10ft to your current speed. 

The healing amount increases by one die when you reach 9th level (2d6), 13th level (3d6) and 17th level (4d6).

Physical Check-up

Starting at 9th level, you learn how to analyze your foe and take advantage of it. As a bonus action, you can spend 20 Vitals to make a Wisdom (Medicine) check or a Wisdom (Perception) check to pinpoint a creature's weakness. You must see the creature to use this feature. If you roll a 20 or above, the next attack against this creature has advantage.

You can use this feature twice per long rest, 3 times at level 13 and 4 times at level 17.

Hemorrhagic Strike

At level 13, you learn how to execute precise strikes at enemies' major veins. Once on each of your turn when you hit a creature with a weapon attack, you can spend 30 Vitals to force the target to make a Constitution saving throw (DC equal to 8 + your proficiency bonus + your Wisdom modifier). If the save fails, the target takes 2d6 necrotic damage at the start of its turn and its speed is halved. The target can repeat the saving throw at the end of each of its turn, ending the effect on itself on a success.

You can use this feature a number of times equal to your Wisdom modifier (a minimum of once). You regain all expended uses when you finish a long rest.

Flatline

At level 17, you gain the ability to empower your weapon with your Vitals, turning it into a deadly magical weapon. As an action, you can spend a number of Vitals to execute a target within range. Make an attack roll against the target. If it hits, you deal damage equals to the number of your spent Vitals. You can only spend a number of Vitals equal to or lower than half of your maximum Vitals pool.

You can only use this feature once every short rest.