You excel at surgeries in and outside of combat. Tourniquets, bone-saws or plain old stitching are second nature to you and you can heal creatures without expending Healing points.
Features
Level 3: Surgery
Use your Surgery tools to stitch up a creature. During a Short Rest you can take 10 minutes and heal a creature equal to your Proficiency Bonus + Intelligence Modifier. The creature can still benefit from triage and spending its own Hit Dice.
Level 7: Improved Triage
You can perform emergency triage in the heat of battle. When a creature is below 50% of their Hit Points you can add a free d8 to your Combat Healing.
Level 11: Bionics
You can replace a creatures limbs or organs with mechanical components. Make a Medicine Check during Down Time or a Long Rest to install the new body parts. On failure, a body part can be lost or even death can occur.
Level 17: Master Surgeon
During a Short Rest, you can restore one creature to full Hit Points. You can only perform this surgery once per creature until they've completed a Long Rest.