The Medi gun is Medic's secondary item, unlike the other classes where its either a shotgun, pistol, or in the Sniper's case, SMG. Very little is known about the substance that comes from it, other than that it comes from Medic's pack on his back. Which might explain why Medic is the only class that can heal overtime.
Pressing and holding the Primary fire while the Medi Gun is equipped causes a beam to lock out on a patient and heal any damage he has taken, along with Overhealing a full healed player. Healing the patient builds up your Ubercharge meter. Pressing the Secondary fire when you reach 100% Ubercharge grants invulnerablility for you and your patient for 8 seconds. But be careful. If you die before you pull the trigger, you loose it all.
- Damaging your self while being healed by a Medic causes the Ubercharge meter to build faster. So if you want an Ubercharge ready before the gates open in setup, that's a way to do it. But don't kill your self in the process.
- When taking out a Sentry Nest with an Uber, run ahead of your patient so you take the kick back and bullets of the Sentry while the rest of the team push forward to take it out
- If you find that your the last one alive in an area, and you have 100% uber, use it. A wasted Ubercharge with an alive Medic is better then a lost one with a dead Medic.