ÜberCharge

ÜberCharge is a skill that is used by The Medic. When used, it makes both Medic and his healing target completely invincible for 8 seconds. Other mediguns give different ÜberCharges.

Stock Medigun
The stock Medigun's ÜberCharge makes the target completely invincible for 8 seconds.

Kritzkrieg
The Kritzkrieg's ÜberCharge gives the target guaranteed critical hits for 8 seconds. But it does not make you invincible, so be aware of that.

Quick-Fix
The Quick-Fix's ÜberCharge heals both Medic and the target at an accelerated rate and also nullifies knockback.

Vaccinator
The Vaccinator is uniqe in the way that it does not build just one ÜberCharge at 100%, but 4 ÜberCharges at 25% each. These ÜberCharges provide 75% resistance to a certain kind of damage. The resistance cannot be changed mid-charge.