I AM THE ÜBERMENSCH!
» The Basics: Increase the patient's metabolism rate enough to promote cell regeneration and repair tissue damage. Additionally, it will also remedy diseases and sickness by promoting the antibodies to react faster. However, if the medi gun is focused on the patient for too long, there will be an overflow of energy. The charge will not work without the device that can contain such pure energy, it will only heal.
THE MEDI GUN
It promotes cell regenation to the point where the patient is nigh invulnerable but not so much that sustained damage can't stop them. It even affects their outer appearance, both with looks ( pure red, glowing yellow eyes ) and texture ( it feels like metal, the pure red skin ).
It gives the patient a huge burst of adrenaline ( the patient will also use the modified heart they need for the ubercharge so as not to work out their cardio ) and gives a temporary second skin to the muscle fibers so they won't tear themselves apart. This also affects their weapons, where the metal becomes extremely hot but not to the point that it melts, and it affects the gunpowder by intensifying the coponents.
Additionally, it produces a non-lethal byproduct with similar effects to cannabis that is named Kritz. Recommended method is through smoking. However, it is not toxic, and it heals and does not destroy the lungs at all. The doctor is able to collect the content and purify it for a more intense effect if he wishes to.
THE QUICK-FIX; PROTOTYPE
» Healing Factor
It increases the healing effect of the medi gun, therefore increasing the metabolism rate. With that, there is a "lasso" effect that forces the doctor to — if healing Soldier, Demoman, or Scout — run as quick as those faster than him. The lasso effect does not work with those slower than him.
A special fuse busted, and so invulnerability can no longer be activated because god knows why. If someone fixes it, hypothetically it may just work again. If it does work, only the patient will gain the invulnerability effect and not the doctor
BUT DOKTOR, WHY CAN'T IT HEAL DEMO'S EYE/CERTAIN INJURIES?
» the wound wasn't fresh; it's already healed. can't do anything about that unless the doctor operates/tears it all off and lets it heal via medi gun. also, mystical demonic eye entity.