- 1 Background
- 2 Strategy
- 2.1 ÜberCharge utilities
- 2.2 Using the ÜberCharge
- 2.3 Defense against ÜberCharge
- 2.4 Using the Kritzkrieg
- 2.5 Defending against Kritzkrieg
- 2.6 Using the Quick-Fix
- 2.7 Defending against Quick-Fix
- 2.8 Using the Vaccinator
- 2.9 Defending against Vaccinator
- 2.10 Chain ÜberCharge (Medi Gun)
- 2.11 Chain Übercharge (Kritzkrieg)
- 3 ÜberCharge combination strategies
- 3.1 ÜberCharge + Kritzkrieg
- 3.2 Kritzkrieg + Megaheal (Quick-Fix)
- 3.3 Kritzkrieg + Vaccinator
- 3.4 ÜberCharge + Megaheal
- 3.5 Megaheal + Vaccinator
- 3.6 ÜberCharge + ÜberCharge / Kritzkrieg + Kritzkrieg
- 3.7 Megaheal + Megaheal
- 3.8 Vaccinator + Vaccinator
- 3.9 ÜberCharge + Vaccinator
- 3.10 More than two charge types
- 4 See also
The ÜberCharge is an ability of the Medic that enables himself and his healing target to become fully invulnerable to damage. ÜberCharge is built up mainly by healing teammates with the Medi Gun and has the ability to turn the tide of the battle when used offensively, and lock down the enemy team when used defensively. In addition to the standard Medi Gun, which gives invulnerability (or invuln), there are three other variations: the Kritzkrieg gives the Kritzkrieg ÜberCharge (KritzCharge or Kritz for short) that enables the patient to deal guaranteed Critical hits for the duration of the charge, the Quick-Fix Medi Gun instead grants a MegaHeal effect granting tripled healing rate and immunity to movement impairing effects for both the Medic and his patient for the duration of the charge, and the Vaccinator grants the Medic and the patient 75% resistance to either fire, explosive, or bullet damage.
Medics have two tools at their disposal that can assist in building ÜberCharge, or mitigate the loss of ÜberCharge.
The Ubersaw is an unlockable melee weapon for the Medic that can add 25% to the Medic's ÜberCharge meter upon successfully hitting an enemy with it, grant 100% charge on a successful taunt kill, or provide 50% Übercharge if the taunt is used on an Übercharged target. As such, it is an extremely powerful tool that can change the balance of ÜberCharge deployments on both sides, depending on how it is used.
- One of the most important things to remember about the Ubersaw is that it attacks enemies at a 20% slower rate, with a maximum rate of one hit per second. As such, for Medics that want to be able to defend themselves against attackers, using the primary weapon instead is often safer in protracted battles.
- Medics equipped with the Ubersaw should keep in mind the current progress of their ÜberCharge meter before attempting to attack enemies to further build ÜberCharge. A Medic with a small amount of ÜberCharge built up can quickly increase progress by attacking enemies and has little to lose by failing; on the other hand, a Medic with a large amount built up risks losing the Über if killed while attacking, whereas the rest of the meter could be completed safely by simply healing teammates.
- The class, state, and awareness of enemies should also be kept in mind. Whereas attacking a Spy who is at low health or a cornered Scout behind friendly lines is relatively safe, as well as unaware Snipers, attempting the same on an aware Pyro or Heavy will more than likely result in death.
- Remember that it is not necessary to kill an enemy with the Ubersaw in order to build additional ÜberCharge. Using hit-and-run tactics can allow Medics to quickly add 25% to their meters by hitting an enemy once and then retreating behind teammates, and is often less risky than fighting to the death.
The Vita-Saw is a melee weapon for the Medic that allows players to retain up to 60% of their ÜberCharge meter upon death — the amount of ÜberCharge retained depends on the number of Organs harvested by hitting enemies, with up to 15% ÜberCharge retained per organ (capping at 60% ÜberCharge retention at 4 Organs). Using the Vita-Saw, like the Ubersaw, can change the dynamics of ÜberCharge deployments on both sides.
- The drawback to equipping the Vita-Saw is that the Medic will have a maximum of 140 HP instead of 150. Players using the Vita-Saw should keep this in mind and play more cautiously.
- The Vita-Saw's greatest strength lies in decreasing recovery time upon death, as building up the ÜberCharge meter upon respawn requires less time. This can be used to surprise the enemy team by having an ÜberCharge ready at a time when they believe they are still safe from one.
- Like the Ubersaw, the Vita-Saw encourages Medics to enter combat in order to harvest Organs and increase ÜberCharge retention. Unlike the Ubersaw, the benefit of the Vita-Saw is hard-capped. Therefore, the Vita-Saw encourages Medics to refrain from entering combat after harvesting 4 Organs, as once 4 Organs have been harvested, attacking enemies yields no further benefit and the chances of being killed in combat are somewhat increased by the Medic’s reduced max health.
Using the ÜberCharge
- The Medi Gun's ÜberCharge is best used to break through entrenched enemy defenses. The invulnerability that it grants allows buddies to survive in situations where they might otherwise be quickly killed. Use this to destroy as many enemy buildings and kill as many enemies as possible to allow teammates to follow up easily.
- Delay using the ÜberCharge until the last possible moment. Try to wait until one or both of the pocket have received damage before activating the charge. Deploying the ÜberCharge as late as possible gives the pair more time to destroy enemy buildings or kill enemy players while invulnerable. The ideal time to deploy the ÜberCharge is when you or your patient is extremely low on health; however, it's better to deploy an Über a bit early than to have one of you die before you activate it.
- Pop it, don't drop it. If you are on low HP and are trying to wait for the best time to pop ÜberCharge, it is better to pop it early than to die with full charge.
- When ÜberCharged, focus more on clearing enemies and destroying buildings than on trying to achieve an objective, as ÜberCharged players cannot capture Control Points, push the Payload cart, or take the Intelligence while the ÜberCharge is active.
- Knockback from explosives, compression blasts, Sentry Guns, and the Force-A-Nature is an ÜberCharge's greatest opponent, so whenever possible, have the Medic go first and draw fire. Both the Heavy and the Pyro are more effective close up against Sentry Guns.
- Be especially wary of Pyros, as they can easily use their compression blast to either delay or, worse, pin Medics into a corner and render the ÜberCharge useless. Remember to kill Pyros first to prevent this from happening.
- If another teammate is the recipient of an ÜberCharge, be sure to follow him and his Medic and use them as a moving shield. Remember that while they are invulnerable, there is only so much a Medic's patient can do, so be sure to assist them in attacking the enemy.
- ÜberCharged pairs attract a lot of fire even while charged, and the enemy will want to take revenge on them as soon as the charge ends. Use this distraction to move onto Control Points or kill preoccupied enemies.
- If, in response to a friendly ÜberCharge, an enemy Medic activates his or her own, try to ignore them and bypass them for other targets. Focus on attacking what can be destroyed or killed instead of on what cannot. Leave the area quickly once your charge starts to run out, as they will still be invulnerable once it ends, and target you.
- The Medi Gun can be used to grant multiple players invulnerability at once by rapidly switching between healing targets. However, the ÜberCharge meter will drain more quickly by switching healing targets to more than one individual while ÜberCharging. This is called "flashing Über".
- Watch out for instant death traps, like the pits around the Capture Point in Nucleus and point E in Steel, because invulnerability doesn't protect against them.
- A solo Medic with a full ÜberCharge meter can activate the ÜberCharge to avoid taking damage, then quickly switch to the Ubersaw and attack enemies to rebuild the ÜberCharge meter, then switch back to the Medi Gun to avoid damage. This is called the Solo Medic Strategy. This is not as effective as deploying it on a teammate, so only use this as a last resort.
Defense against ÜberCharge
- The best defense against an ÜberCharge is another ÜberCharge. At least one defending Medic should build an ÜberCharge and save it for when attackers come in with one of theirs. An ÜberCharged pair should try to body-block the opposing ÜberCharged pair (physically stand in their way and prevent them from moving forward) to waste their ÜberCharge time, then finish them off afterward.
- After setup time, both teams are bound to have an Übercharge ready. One tactic is to let the other team use up their Übercharge first, then let your team's Über attack the other team by surprise. Make sure your team's Medic doesn't die during the opposing Übercharge.
- Although they cannot be hurt, ÜberCharged pairs can still be knocked back by Sentry Guns, rockets, either of the Demoman's weapons, or compression blasts. Target the Medic to launch him away from his teammate, and once he has been blasted far enough away, his link with his patient will be broken, rendering the patient vulnerable to attack. Once the Medic's ÜberCharge runs out, attack him.
- Demomen are good counters to an ÜberCharge. Lay a line of Sticky bombs on the ground, wait until one of an ÜberCharged pair steps on it, then detonate, sending that player flying into the air.
- The trap can also be detonated after one of the pair crosses it, but not the other, to send the two flying in opposite directions. This is useful for both eliminating the threat of the ÜberCharge and killing the player who is launched towards your team.
- Remember to use obstacles and terrain to amplify the effects of a sticky trap. Try to use the explosive knockback to push one or both of the pair into corners, or off ledges.
- Note that stickybombs on walls and ceilings do not significantly affect an ÜberCharged pair, they must be on the ground and in close proximity of each other, and at least two bombs are required for a noticeable effect. Different classes have different weights — an ÜberCharged Heavy may take 5 or more stickies to successfully blast away, while the lightweight Medic can be launched airborne with two or three bombs.
- Soldiers can bounce an ÜberCharged pair around by firing rockets at their feet. Try to push them into corners or off the map. If possible, try to bounce the Medic only in order to separate the pair, leaving the patient vulnerable to attack.
- A very good way to deal with ÜberCharges is to use the Pyro's compression blast. Using the compression blast's knockback, it is possible to delay an ÜberCharge for a significant amount of time.
- If possible, try to physically separate the Medic from his patient. Most of the time a Medic's patient will push on ahead and not realize that he is without ÜberCharge until it is too late.
- Against a Soldier or Demoman, the Pyro can simply deflect the explosives to minimize the amount of damage caused by the assault.
- The most common target for an ÜberCharged pair is a Sentry Gun. The Engineer has three choices: hide behind his gun and repair it faster than it gets damaged, pick it up and carry it away from enemy fire, or abandon it and rebuild as soon as possible.
- If the ÜberCharged pair includes a Heavy, and they are not too close or the ÜberCharge is almost done, the Engineer can survive if he hides behind his Sentry and has a Dispenser behind him to keep healing him and supplying him with metal to repair his gun. If they get close, however, it is better to flee.
- If the ÜberCharged pair includes a Pyro and get close, the Engineer will likely die, and the gun a few seconds later if the Pyro has enough ÜberCharge time left. Consider fleeing if they get close.
- If the ÜberCharged pair includes a Demoman, the Engineer should stay if the Demoman is firing regular grenades. He may die, but he will probably keep his gun alive long enough to survive the ÜberCharge. However, if the Demoman gets three sticky bombs under the Sentry Gun, the detonation will destroy even a Level 3 non-wrangled Sentry Gun. Pick up the Sentry Gun, destroy the bombs with the Shotgun or Short Circuit, Wrangle it to reduce damage, or abandon it and retreat.
- Using the Wrangler, it is possible to save a Sentry Gun from some ÜberCharges. When a Sentry Gun is wrangled, it resists 66% of all incoming damage.
- The Rescue Ranger can also be used to both repair and pick up the sentry from a distance, allowing you to save it from an incoming enemy.
- It may also be possible to destroy stickies with the Shotgun or Short Circuit, if an enemy Demoman is firing them slowly enough or is very inaccurate. However, after the second bomb lands, the Engineer should flee from the Sentry Gun and either Wrangle or retreat to rebuild. See Engineer Strategy for more information.
- ÜberCharged pairs can be slowed down by body-blocking them (physically standing in their way and preventing them from progressing). While this will almost certainly result in death, it could cost the pair one or two seconds of precious Über time, especially if they are focused on a different objective. Try to keep strafing to continue to block one or both of the pair as they attempt to maneuver around, and if possible, try to block only the Medic and allow the patient to continue forwards. Scouts armed with the bullet-dodging effects of Bonk! Atomic Punch are especially effective at this, and can potentially waste all 8 seconds of an enemy's ÜberCharge.
- Although the opportunity rarely presents itself, it is possible to Telefrag those under the effects of an ÜberCharge. Any enemy standing on a Teleporter Exit will be instantly killed if an enemy uses it, reagardless of whether they are invulnerable or not. When this occurs, it is usually due to sheer luck and the ÜberCharged pair not noticing the exit.
Using the Kritzkrieg
- A Soldier or Demoman is often a good target for a Kritzkrieg ÜberCharge, due to their weapons' significant damage and splash radius. A properly timed attack can wipe out a crowd of enemies before they can react.
- Use a Kritzkrieg ÜberCharge on a Soldier using the Buff Banner to help him quickly build up rage with the critical hits, allowing him to follow up with Mini-crits once the charge expires.
- Soldiers using the Cow Mangler 5000, however, are a poor choice, as the weapon's shots will only deal Mini-crits instead of full Critical damage.
- During setup time, try to help a Demoman deploy Critical sticky bombs near the enemy spawn. The blast radius should be enough to kill most of the opposition. If possible, try to find one carrying the Scottish Resistance, so that the Demoman can separately detonate his bombs.
- If fighting on a wide-open and outdoors map, a Heavy can make a good target for a Kritzkrieg ÜberCharge. Remember that because the Minigun is a hitscan weapon and that Critical hits do not suffer from damage falloff, a Crit-boosted Heavy, even at long range, is still extremely dangerous.
- When defending a point, either wait until the enemy ÜberCharge runs out before activating a Kritzkrieg charge or utilize the additional damage from the crit-boost to generate extremely heavy knockback, forcing the enemy off the point.
- Always be wary of your surroundings as well as the positions of any enemy players. Medics using a Kritzkrieg ÜberCharge will not have the invulnerability that the Medi Gun provides. Spies and Snipers can easily stop the charge abruptly with a backstab or headshot.
- The ÜberCharge meter of the Kritzkrieg increases 25% faster than the standard Medi Gun, making it easier to build a full ÜberCharge before dying.
- Due to the Kritzkrieg's faster charge time, it is possible to use it to kill enemy Medics who are using the standard Medi Gun before they can fully build up an ÜberCharge.
- Remember that critical hits don't affect buildings, which makes the standard Medi Gun a better choice for destroying Sentry Guns.
Defending against Kritzkrieg
- In general, always try to kill the Medic as quickly as possible. As the Kritzkrieg does not grant either the Medic or patient invulnerability, they can still be damaged and killed.
- If a Soldier has the Battalion's Backup, activating it will nullify all Critical hits in an area around him, including an enemy Medic's Kritzkrieg charge.
- As a Pyro, it is possible to deflect incoming explosive projectiles if the Kritzkrieg target is a Soldier or Demoman. If possible, try to deflect any explosives back at the Medic to end the Kritzkrieg charge as quickly as possible.
- As a Soldier or Demoman, use explosive jumps to gain a height advantage with which to attack the Medic. Usually the Medic's patient will be too focused on trying to kill teammates on the ground to notice threats from above.
- If you attack the Medic while he is giving his Medic buddy the effects of the Kritzkrieg, try to approach the Medic from behind or the side, not head-on; exposing yourself to a volley of Critical hits will likely kill you before you can inflict significant damage.
- Snipers can take shots at a Kritzkrieg-charged duo from the back lines; a fully-charged bodyshot or an uncharged headshot will almost always kill the Medic.
Using the Quick-Fix
- In general, the Quick-Fix is best used capturing objectives quickly. It has a 40% faster heal rate and a 10% faster ÜberCharge build rate compared to the default Medi Gun. It's great for getting that last push for the objective — despite only having 50% overheal compared to any other Medi Gun.
- Oddly enough, the Quick-Fix's overheal penalty allows the Medic to build his ÜberCharge fastest when out of combat. Because teammates never reach 150% max health, the Quick-Fix always builds charge at its maximum rate.
- The Quick-Fix's rapid healing can be used to sustain a large group and is extremely effective in coordinating pushes. When using it, try to follow the bulk of your team's force and keep them above 50% health. Use the Übercharge when the team is under heavy fire and heal as many teammates as possible.
- When the ÜberCharge is deployed, the patient and the Medic will be healed at triple the default healing rate, and both will be immune to movement effects such as Knockback, Stun, and Slowdown.
Defending against Quick-Fix
- Make a Medic with the Quick-Fix your primary target when close to an objective or healing a group. Try to take them out before they get a chance to deploy their Übercharge.
- The Quick-Fix, like the Kritzkrieg, does not make the Medic and his target invulnerable. When a Medic deploys an Über with the Quick-Fix, focus all of your team's fire on the Medic to give you a chance of taking him down quickly.
- A Sniper or Spy can instantly kill a Quick-Fix ÜberCharged Medic with a single backstab or headshot. As Sniper, remember that the Medic is also overhealed; charge your shots before firing.
- Don't try to use Knockback to stop the Übercharge. Try to separate the Medic from his pocket.
Using the Vaccinator
- Whereas other ÜberCharges are primarily built up over a long time and released at an opportune moment to blow a hole in the enemy lines, the Vaccinator stacks up multiple charges very quickly and is more effective at constant pressure than a single push.
- It is important to know the enemy team's composition and loadouts. A team with mostly Heavies, Scouts, Snipers, and level 2 Sentry Guns should be easy to push into with a bullet-resisting Über, while stock Demomen and Shotgun-less Soldiers will be stymied by an explosives-resisting Über. Fire is a much more situational resistance and should be employed in the face of a Pyro ambush more than as an attempt to move up.
- Patients tend to be more cautious with a Vaccinator Über than other ÜberCharges due to the risk of taking unresisted damage from unexpected sources. Proper communication is necessary to ensure the patient and Medic know what the plan is.
- It's important to note that you are vulnerable to all melee weapons. Keep alert and watch out for Demoknights or Spies, who can easily kill you in one hit.
Defending against Vaccinator
- The Vaccinator's main weakness is that its Über can only have one resistance per charge. Switch weapons to something that is not resisted before attacking the Medic; this will force the Medic to use another charge or allow you to ignore the majority of the damage resistance.
- If you have no weapons that aren't currently being resisted, then do not attempt to attack the Übercharged pair, as it will do minimal damage and simply allow the Medic to build his ÜberCharge faster.
- The Vaccinator will not protect players against melee attacks. If you have no other option, try charging the Medic with your melee weapon while his patient is distracted.
Chain ÜberCharge (Medi Gun)
To successfully perform this technique, at least one player must have built up an ÜberCharge beforehand. The first player must then deploy his charge on the second, who in turn must use his Ubersaw to attack enemy players and subsequently build up his own Übercharge meter. Once it is ready, the second player must then quickly deploy his ÜberCharge on the first Medic (usually before the first ÜberCharge is used up), who in turn switches to his Ubersaw and attacks enemies to build up his ÜberCharge meter. If this chain can be repeated successfully, both Medics can remain invulnerable for extended periods of time whilst killing a multitude of enemies.
The technique requires good communication between the two Medics. Both should be aware of the status of both ÜberCharges in order to continue the chain uninterrupted, as well as knowing when to break off the chain should something go wrong.
Chain ÜberCharges can be an effective strategy for clearing a certain area of enemies, pushing through a strong defense, or heading off an incoming attack. It is less effective, however, against buildings or for completing certain objectives such as capturing a point. The chain can be easily broken by Pyros utilizing the Compression Blast ability to separate the Medics, or with Scouts luring the chain into chasing them and wasting time. The attacking Medic, though, is not limited to using his Syringe Gun or Blutsauger to fend such classes off. Slower classes are a priority for the chain, as the Medics can easily reach and attack them.
Should the chain be broken, both Medics should escape the area and regroup later with another ÜberCharge ready.
When using the Invulnerability Überchain, different tactics should be used based on the classes you are facing:
- Don't bother chasing after a Scout. It is unlikely you will be able to hit them unless they run into your melee range.
- Soldiers are a good class to target. However, try not to put too much distance between you, your helper, and your target Soldier, as they may use their Rocket Launcher to push you away from the other Medic.
- Pyros are better off left alone, considering they can easily airblast your chain apart. However, a Pyro using the Phlogistinator is an ideal target since they lack their airblast ability.
- Demomen are slow and therefore good targets. However, watch out, as they may use their explosives to blast you away from your other Medic.
- Heavies are the easiest targets. They lack speed and cannot knock you back while evading you. Their high health also lets you gain a full ÜberCharge from a single Heavy.
- Engineers are a good class to target, unless they are being guarded by a Sentry Gun. Sentry Guns will easily push you back and away from your other Medic.
- Other Medics are not much of a problem to you. However, they move just as quickly as you do and are usually not worth your time to chase.
- Snipers are a good target. They may have their back turned depending on where you encounter them, so it will be easy to hit them with your Ubersaw.
- Spies are a good target. They are just as fast as you but are powerless to push you back. They are unable to backstab you since you are invulnerable. However, they will probably cloak away from you.
Chain Übercharge (Kritzkrieg)
Firstly, the Medic builds up the Übercharge to 100% and uses it on a Heavy with the Holiday Punch. When an enemy is immobilized and starts laughing, the Medic switches to his Ubersaw and performs the Spinal Tap kill taunt on the victim, killing him and restoring the Medic's Übercharge. The cycle is now ready to be repeated again.
This method is far more viable than the double-Medic Chain Übercharge because when things do not go as planned, the Medic and Heavy can easily fend for themselves, while the Medic pair does not have the same defensive capability. However, since this method does not use the Invulnerability Übercharge, the Heavy and Medic are still vulnerable to enemies while chaining. Even though this method requires the Heavy to land only a single hit on an enemy with the Holiday Punch while the double-Medics require 4 strikes of the Ubersaw, a Heavy is much slower than a Medic, forcing the Heavy to rely on ambushing an enemy (and also because he is not Invulnerable).
Tactics for the Kritzkrieg variant are similar to the Medi Gun variant, with the exception that you need to ambush enemies rather than approach head-on because you're slower and more vulnerable. Because you are not Invulnerable, in the event where you approach multiple enemies, the Heavy needs to kill off all enemies with his other weapons. A last enemy can be spared so that he can be used for the Chain Übercharge.
ÜberCharge combination strategies
Deploying multiple ÜberCharges on one patient can be very helpful. However, it can also be wasteful, depending on how it's done and what types of charges are used.
ÜberCharge + Kritzkrieg
This is the best type of combination ÜberCharge. A player who is completely invincible and can deal critical hits can be a dynamo of pain against the other team. However, the Medic deploying the Kritzkrieg should be cautious, as he is still vulnerable, and the entire assembly remains vulnerable to knockback. This combination is best used versus a large force of high-health players, as it can quickly take down even fully-overhealed Heavy-Medic pairs without trouble.
Kritzkrieg + Megaheal (Quick-Fix)
This combination is the second-best one. While it doesn't provide the invulnerability of the ÜberCharge, the patient is receiving an increased healing rate and the standard healing and overheal of the Kritzkrieg. The Kritzkrieg Medic should still hang back, as he is vulnerable. However, the Quick-Fix builds ÜberCharge 10% faster than the stock Medi Gun, allowing for more frequent use and easier coordination. This combination is best used versus a large force of Soldiers, Demomen, and Pyros, as it deals significant damage while preventing knockback which could separate the Medic and patient.
Kritzkrieg + Vaccinator
Similar to the previous combination, with the patient taking less damage from particular sources instead of being healed of damage quickly. The Vaccinator Medic is not as vulnerable as a Quick-Fix Medic would be, and the stream of critical hits erupting from the patient should deter the usage of unresisted melee attacks. The Vaccinator also builds ÜberCharge 67% faster, allowing this combination to be used often.
ÜberCharge + Megaheal
This combination is less effective than the previous ones, as the Megaheal's bonus healing is wasted on an invincible player. However, it will still provide knockback immunity, making this combination ideal for assaulting a large sentry nest or sticky trap, where the patient would be otherwise rendered useless by knockback. Although the Quick-Fix Medic has an increased heal rate, he should be cautious, as he is the most vulnerable.
Megaheal + Vaccinator
Strictly speaking, resisting damage of one type and quickly healing damage from other types is not much of an improvement over a single invulnerability ÜberCharge. That said, this combination has the Quick-Fix's immunity to knockback and can be built much quicker than a regular Über.
ÜberCharge + ÜberCharge / Kritzkrieg + Kritzkrieg
Deploying two charges one after another in order to double the length of the effect can be effective in heavily-fortified areas that a single Über cannot break through. However, unless the recipient is a Heavy or a Pyro, they will be forced to spend most of the second charge either reloading their main weapon or firing a secondary one, which lowers the effectiveness of this strategy. Often, a team may best effect such a push with two separately affected teammates.
Megaheal + Megaheal
The increased heal rate makes the target practically invulnerable to any damage which isn't instantly lethal. This pairing builds 25% faster than a standard Übercharge, but provides similar invulnerability.
Vaccinator + Vaccinator
If the two Vaccinator charges are on different resistances (bullet and explosive being the best choice for such a combo due to fire being comparatively rare), the patient becomes heavily resistant to the majority of weapons and so can wade through enemy fire without taking much damage. However, the overall effect is similar to a Megaheal without the knockback immunity. Only one Medic with two Vaccination charges is required to use this combo effectively, making it viable for single Medic setups.
ÜberCharge + Vaccinator
As the Vaccinator's sole purpose is to reduce incoming damage, combining it with an ÜberCharge is pointless. The only reason to use this would be an urgent heal for the Vaccinator Medic if a health kit is not nearby. Due to the fast ÜberCharge build rate of the Vaccinator, this is not too much of a waste.
More than two charge types
A skilled player with a triple Über can be very devastating indeed to the enemy team, being immune to everything thrown at them while blasting critical hits. However, putting all the Medics' eggs in one basket is more often than not a poor idea - a single player immune to everything can be avoided, but three players each under the effect of a different charge is much harder to deal with, and so would be a better strategy.