The Tank

The Tank is a muscular Special Infected of gigantic proportions. The infection has caused a huge amount of muscle growth, granting it superhuman strength. This monster is capable of throwing large items such as cars or blocks of concrete it rips out of the ground, and bashing through otherwise impenetrable walls. The Tank keeps a high profile, able to be heard by the Survivors from a great distance due to its loud growls and the thrashing it makes when running. The immense strength and sheer toughness of the Tank make it a terrible foe in combat, especially to inexperienced or uncoordinated Survivors.

Occasionally, players are able to take on the role of the Tank in Versus mode. When the Director has given them control of it, the Tank has a frustration meter that slowly drains when he doesn't hit the Survivors, the frustration meter also depletes as long as the Tank can not see the Survivors. This was employed to prevent players from camping away from the Survivors for long periods of times and using out-of-character strategies. Once the frustration meter is depleted, control of the Tank is given to another player if available. If the second player's frustration meter is depleted, the Tank becomes AI controlled. Also, when players are controlling the Tank, they can break down walls highlighted by yellow cracks. Though multitudes of Common Infected can break down the walls, as can other Special Infected, only Tanks can break through steel. There was also an update for both the Xbox 360 and PC versions of the game where certain objects that can be smashed are highlighted in red.

The number of Tanks depend of the server preferences, the game difficulty and by the Director. It is very rare that there is more than 1 Tank per chapter. In finales, two Tanks are spawned during the initial rescue, though not at the same time, with the rescue vehicle arriving after the second Tank is killed. When the Survivors are making their way to the rescue vehicle, many Tanks can be spawned at once. There is a small chance of the Director spawning two Tanks at once outside the finale, but it is extremely rare for it to happen. The Tank is heralded by a brief ceasefire in finales, where the hordes will stop rushing (unless a Survivor has been covered in Boomer bile), allowing players to catch their breath. In other chapters, however, there are generally fewer Common Infected around, almost making things eerily quiet, a calm before the storm. It's possible that this is because the other Infected have fled, as the Tank seems to eviscerate anything standing between it and its target without hesitation, although the Tank does not attack the Infected intentionally.

Extent of Mutations
The Tank has been heavily mutated by a strain of the infection. It has developed immense, thick muscles that not only indicate its incredible strength and endurance, but make it nearly bulletproof, resulting in extreme firepower being needed to take one down. However, this increase in muscular tissue makes it a large target, and, like other Infected, is highly flammable. Its mind has also been heavily affected, making it extremely bloodthirsty, even for an Infected, but is not affected by minor distractions such as the flashing lights on pipe bombs, and does not appear to be attracted by things such as car alarms going off. The Tank's lower jaw seems to be missing and the tongue flops out, possibly because of the immense chest it has. Because of its massively increased muscle growth and the small legs, the weight of its upper torso can't be lifted by its legs, forcing it to move on all fours, similar to a gorilla. In Left 4 Dead 2 the Tank has lost his hair and is completely bald. 

Survivors

 * In some levels there will be small passageways. The Tank can get stuck in these passages  giving you lots of time to kill him.
 * Listen carefully for the Tank, make sure you can distinguish him from Hunters, Smokers and Boomers (the sound of its growling). It is difficult to do so, but one can sometimes hear a Tank breathe and grunt before it attacks. You may want to turn subtitles on, so if there is a Tank on the map, but the music cue hasn't started yet, then the growls and roars will appear on the subtitles and you will have time to prepare for an attack. Sometimes part of his body is sticking out, like an arm, due to how big he is. If you can see it, you can get ready for the unavoidable fight. By the time the Tank is in your line of sight, it is often too late to plan an effective defense. In fact, upon hearing the Tank, some players may want to simply try to hide until the meter builds and then while the computer is thrashing, run from the noises. If there are no obstacles, run backwards so that you can shoot on the run. A Survivor with sufficient health can outrun the Tank. Otherwise, go ahead and open up on it. Be aware that the nearest Survivor that shoots the Tank is the target. Running ahead of others may end up triggering a Tank and your teammates won't be ready for it.
 * Throw a molotov cocktail in its path to set it on fire and slowly eat away at its health. This method ensures the Tank's death if you are unsure of your ability to down the beast with sheer firepower. However, setting the Tank on fire will increase his running speed (this applies only in campaign mode; a flaming Tank in Versus mode moves slower). Shooting will slow him down significantly. All in all, shooting a burning Tank will make him slower than leaving him untouched. Always make sure that every Survivor not being chased by the Tank is shooting at him.
 * The Tank can find you even in the dark. So don't think that you are safely hidden inside a closet with your flashlight off.
 * If you are lucky enough to be near a thick tree, you can lead the Tank a merry dance by keeping the trunk in between yourself and him. He can't go over a tree and he can't rip it up either. In fact, any static physics object can allow you to avoid the Tank.
 * The Tank can knock down the beginning safe room door, unless you run into the door constantly. In this situation, he cannot get through, unless you are really unlucky. (The Tank can't destroy the door on PC version patch 1.0.1.3)
 * The Tank climbs obstacles much more slowly than he can run; exploiting this fact will provide you with more uninterrupted firing time.
 * If you are incapacitated, do not shy from using pistols on the Tank since every bit counts.
 * If you're in an area where falling is possible, such as the Rooftop Finale, make absolutely sure that you are between something solid and the Tank, so that its attack won't launch you on an incredible 30 story journey to your death. However, if you're a dare devil, and are the Tank's current target, run off the edge (don't jump)and he should follow you off the edge (The Tank keeps his target even if they are incapacitated). Once the Tank falls, have your teammates help you to your feet and keep on going.
 * Generally, you need 51% health (green health bar) to defeat the Tank, according to the Left 4 Dead manual, though less is required on maps with obstacles to block the Tank.
 * If you have pills and someone else's health is in the red, give them your pills. This can prevent them from getting incapacitated. Also, pills provide 50% health so giving them pills will let them run faster.
 * If melee'd, the Tank will chase whoever hit it; this is extremely useful when a Survivor is incapacitated and is being pounded on, enabling a healthy Survivor to lead the Tank in circles while someone else gets the Survivor back up and into the fight. However, the incapacitated Survivor must not shoot the Tank after it has been hit or else he'll turn right around and keep on punching them.
 * It is very hard to aim for the Tank's head as it is being obscured by its massive muscle mutations, but if you do get a clean shot, take it. However, shooting the Tank's head will not do extra damage, it will just stun him for a second.
 * Avoid bunching up together such as in a closet or corner and trying to unload onto the Tank while he assaults you. Not only does it make you an easy target if there is a prop around such as a log or forklift to instantly incapacitate everyone, but the Tank's punch now hits multiple Survivors at once, and hiding in a closet can entomb you inside of it. Stay apart but within range of your teammates if any Special Infected try to pick them off.
 * If there is a minigun near by, you can use it to force the AI Tank to switch targets. The AI Tank always goes for the person mounted on the minigun.
 * Try to get the Tank go in through a window, vent or any other small area, it will give you a few more seconds to kill him.
 * Try to catch the Tank with a friend (both equipped with auto shotguns), you might be able to play pinball with the Tank by shooting him, then letting your friend shoot him thus making him run to your friend. Repeat that process until that Tank is dead.
 * If you and your friend(s) are equipped with auto shotguns you should be able to kill the Tank before he/it causes damage to anyone. (auto shotgun damage ~3000 damage per clip, see Tank health statistics -&gt;)
 * After the crane panic event in the second stage of Dead Air, try lighting the Tank on fire, and making him fall between the building. This will cause the Tanks health to be eaten away and will sometimes kill the Tank before it gets back up. If no one else shoots the Tank, it would get you an easy "Man vs Tank" achievement.(Works on expert as well as the other difficulties)
 * If you are close to the safe room, The Tank can't get in and you can shoot at him through the door. The only problem will be if you get to close to the door he can still punch you .If your at the start of a level and you run into a tank don;t run back into the safe room on some situations he can break the door and then you will be trapped.

Notes About the Rock Throw

 * The Tank can't move and throw.
 * You'll know when he's going to throw by the absence of the ground pounding noise.
 * Anyone can shoot the concrete out of the air, rendering it harmless. This method, however, is not always fail safe as it takes a more than a couple of bullets from an Assault Rifle to destroy the rock, and a shell from the shotgun at close range. The Hunting Rifle, if equipped, is perfect for sniping those rocks out of the air. The other side to the rock throw is that once it's thrown, you only have half a second to at most two seconds window of opportunity to shoot it or dodge it, depending on your distance from the Tank.
 * If The Tank is controlled by the AI, it can't predict where a Survivor will run. Zigzagging will cause The Tank to throw the rock far from your current location. This does not apply on expert, as the Tank possesses an increased aim and has an easier time predicting where you'll be when the rock reaches you. However, by moving in one direction when he is picking up the rock and then changing directions immediately after he has released it, he will most likely miss. This is because once it's been thrown it cannot change course. Note that this will not work if the Tank is very close.
 * Non-static geometry, such as crates, will not block his shots.
 * You may be unable to dodge a rock if you are limping too badly (i.e.: when your health bar is red or yellow).
 * The Tank has the uncanny ability to locate a chunk of stone beneath its feet regardless of its current location, so don't be lured into a false sense of security in which you think that it can't hurl a block at you from inside the upper floor of a building, or anywhere else for that matter (such as the middle of a rope bridge).
 * If you have sufficient health and the Tank is spawned towards the middle or end of an area, simply run back the way you came and eventually the Tank and will lag behind and die, also don't worry about Infected as an area is usually devoid of them when a Tank is nearby


 * The Tank has a slight recharge of his punch. If it punches at you, and misses, use the 2-3 seconds that it takes to recharge to run behind him.

Infected

 * Avoid crouching through ventilation shafts and windows after Survivors. You will move incredibly slow whilst taking damage and crouching (from weapons such as the auto shotgun and assault rifle, especially), almost to a point where you will find it difficult to move at all. Although this problem has been addressed by Valve, it is never a good idea to move though an area where the Tank is forced to crouch.
 * Your rock throw is usually very underestimated. With practice it can be devastating and deal a lot of damage to the group of Survivors quickly. As a rule of thumb, aim your reticule above, and perhaps ahead of, the target while throwing.
 * Even within melee range you should use your rock throw to hit a Survivor, because this allows you to use your melee attack immediately after.
 * Use concrete projectiles to knock down pesky marathon Survivors.
 * Although you cannot punch through walls, if you get close enough to a wall, you can throw rocks through walls at Survivors on the other side.
 * Even though the Tank was made to charge through seas of lead, a strong Survivor team can take him out without taking damage themselves. In addition, managing to do this gives the team an achievement.
 * Avoid attacking in the open if at all possible, as it can be tough to get to Survivors for a melee attack and it is easy for them to avoid rock throws.
 * It is possible to assist Hunters who have already pinned someone, but the effort required to aim isn't worth it. The reason is that the Tank's attack will kill the Hunter (or any other Special Infected, for that matter) instantly.
 * On the same note, if someone else on your team is playing as a Tank, work with them, but give them a wide berth, as they'll likely kill you by mistake.
 * If you want to succeed in defeating the Survivors and one is pinned by a Hunter, assist your teammate as the Tank by protecting him by running at Survivors, separating them and distracting them which makes them easy targets, it only takes a Hunter a few seconds to dish out some serious damage.
 * Use alternative routes where possible to "sneak up" on or flank the Survivors.
 * If you incapacitate a Survivor, immediately re-target another. If someone has managed to get around you to help their incapacitated friend, show the good Samaritan their mistake by knocking them out, too.
 * If playing on a level where it's possible to knock Survivors off of a high place to kill them, such as chapters 4 and 5 of the No Mercy campaign, do everything you can to knock them over—once they fall, there's no helping them.
 * Tanks can punch cars, forklifts, tree logs and dumpsters large distances.
 * Punchable red highlighted objects instantly incapacitates a Survivor.
 * Hitting cars is faster than throwing concrete.
 * Hitting a car with an alarm will cause the alarm to break permanently.
 * Punched cars will disappear after a while.
 * Using punchable objects effectively can save you health and time, and can also cause panic amongst Survivors as they try to stay clear of flying cars and forklifts.
 * Most of the time, you can hit such an object from any side of your body. Use this to save time walking around objects, because you can just walk up against it and punch the way you need it to go. Additionally, you can aim upwards to throw things in an arc, or toward the ground to have more control of the direction you punch it in.
 * Punch Survivors in different directions to separate them.
 * If the Survivors are indoors, keep attacking one Survivor (choose the one with the lowest health first) until they are incapacitated
 * Be careful using the swing attack on Survivors in wide open, flat areas, as this merely gives them a chance to get away. Charge a Survivor you've whacked as soon as you whack him, going for another whack.
 * Always aim to divide and conquer if you're in a building or in an area with many obstacles. Try to spread the Survivors out by hitting them behind large objects or knocking them out of windows. Separated Survivors allow for other Special Infected to attack and kill them.
 * If the Survivors can't see you, they can't shoot at you, meaning that you will take less damage during your rampage.
 * This helps Hunters to pounce on Survivors, or Smokers to grab Survivors, so they can't come to the group's aid or the group coming to kill the Infected that has them pinned or tied up, leaving you with one less Survivor to kill.
 * Do not attack an incapacitated Survivor if a Hunter or a Smoker already has them locked in a bind. Doing so, while doing some damage to the Survivor, will more than likely kill your teammate.
 * Avoid being set on fire as best you can.
 * Take notice at who has a Molotov before you become the Tank, and avoid these players until the fire they throw burns out.
 * If you hit a Survivor you see has a Molotov, be sure to incapacitate them if you can.
 * If you see somebody about to throw fire, change direction immediately! If worst comes to worst, use the rock throw to hit Survivors.
 * Fire kills a Tank after 30 seconds, and it shows the damage in your health.
 * If you are set on fire, charge the Survivors. You won't have much time to do your damage, every second counts with the Tank.
 * If there's water near you (like in Boathouse Finale), dip in, because this will put the fire out. This also works in the sewer of the No Mercy campaign.
 * Go after any Survivors that get separated from the group unless the others are extremely low on health. One gun on you is much better than three.
 * The March 11th update made it possible for the Tank to hit multiple Survivors at once. Previously, it was a viable defense when playing as the Survivors to group together in a small room or a corner. This was because the Tank could not hit more than one person at a time and would quickly be killed without doing much damage.
 * In the scenario that the Survivors do use the auto shotgun strategy (when all Survivors use an auto shotgun at close range and bunched up), attempt to put as much room between them and you as possible, keep them in your line of sight and attempt to bludgeon them to death with a volley of concrete blocks.
 * Unlike on Campaign Mode, attacking an incapacitated Survivor will do only about 24 damage per hit. Considering incapacitated Survivors have 300 health, it is much easier to simply incapacitate each Survivor one at a time. Choosing not to do so usually makes you a stationary target for everyone to gun you to death. You should really only use the Tank Pound to force the Survivors to come to you or their teammate will die.
 * If you get the indication that you are about to become a Tank, and are currently an un-spawned Special Infected, try to immediately spawn that Infected near the Survivors. This way your team will have an extra AI-controlled Special Infected to help during the attack. Note that in some cases if you spawn to far from Survivors, the Infected AI will stand idle and will not attack.
 * At one time or another, when you are next to become the Tank, you might be spawned right in front of the Survivors, letting them pick at your health. This is bad because you can't move the Tank for a moment after spawning, so when you do get control, your health is already half spent.
 * If this does happen, just charge at the Survivors and attack, don't run. By the time you finally get away, you'd only have about 1/4th of your total health, so when you try to charge them again, they could pick you off just like any Common Infected.

Tank Tips And Tricks Gameplay
http://www.youtube.com/watch?v=Akf-v_7FFQ0&feature=channel_page

Trivia

 * The Tank appears the only Special Infected that has not gotten a significant change in Left 4 Dead 2, the only difference is that he is now bald and seems to have some more muscles.
 * The Tank's ability to hurl chunks of concrete was included when the game developers discovered that because the Tank was so slow, it could be quite underpowered when faced at range.
 * The Tank's corpse floats if you kill it in water, as seen in the Boathouse Finale.
 * Music Cue: Tank
 * In the game's folder for the Tank's music (\sound\music\tank), there are two files, one named "Tank.wav" and one named "Taank.wav". Taank.wav sounds slightly different than Tank.wav, and it is 27 seconds longer. It is apparently played when the Tank appears during a Finale.
 * It would appear that in campaign, despite the fact that it has no need there, the Tank still has a frustration meter, but instead of losing control the Tank simply dies, which can be used to great advantage with competent teammates and the ability to avoid it, especially on expert.
 * Occasionally, the Tank will simply go idle instead of dying off, but will begin attacking again after spotting the Survivors.
 * The Tank occasionally walks backwards, which is glitch when it re-targets a player behind it. However, when he's doing this, and he punches with his hand forward, he still hits you.
 * The terrain the Tank is standing on when throwing a rock is not damaged, appearing exactly the same before and after the attack. In addition, even if the ground the Tank is standing on clearly doesn't contain concrete or rocks to throw, the Tank is able to grab and throw a rock.
 * Tank had an article in X-box's 97th issue. The article read as follows:


 * Dear Humans. This is Tank. You probably know me from hit Xbox 360 game Left 4 Dead. Well, Tank need to get something off chest. It make Tank sad that as soon as you see him, you start shooting at him. Tank not mindless killing machine. Sure, Tank enjoy smashing human skulls to paste. What 12-foot tall, 800 pound, horribly mutated creature wouldn't? But there is another side to Tank. Tank also enjoy stamp collecting, scrapbooking, and updating blog under pen name "Love Muffin". Tank took origami class once at adult-learning annex, but fingers to big, so Tank smash teacher. Got B-minus.


 * So, when you see Tank on the streets of city, instead of shooting, try asking Tank how day is going. You may find that you and Tank have more in common than you think. Of course, Tank will still smash you, but you will die having made new friend. And that make Tank happy.
 * -Tank


 * Very rarely, the Tank will regenerate health. This can be seen on The Church, where if the Tank spawns in the train yard, you can shoot it with all of your shotguns and wait awhile, you can reload and do it again and again, twice, to kill him, where if you shoot him with 20 rounds anyway, he would have died. However, you can only kill a Tank with 20 rounds on normal or easy difficulties.
 * In campaign, when the Tank is set on fire, it runs 30% faster than when not on fire. However, on versus mode, when it's set on fire while controlled by a player, it runs about the same. The AI Tank still runs faster when set on fire.
 * On the rare and lucky occasion that the Tank's spawning system bugs, he will spawn in a place where he is stuck and cannot get to the Survivors. The Survivors will just hear the music and his grunting, but won't be able to see him and he would just die a short time later, due to the frustration meter. However this is extremely annoying if playing as the Tank.
 * The sequence in which the Tank pushes and throws Common Infected in the opening trailer is almost identical to how the Alpha Male Infected shoved and bashed his fellow Infected while charging towards Robert Neville before the ending of the movie, I Am Legend.
 * It was previously possible for a player in Versus to regain frustration by hitting a car even if it didn't hit a Survivor.
 * The Tank is very similar to Half-Life 2's Dog, they're both very strong and share the same idle pose.
 * The Tank, along with the Boomer, are the only Special Infected that take on physical changes in appearance upon death. For example, the Tank's skin becomes dried out and scorched if it dies on fire, unlike the other Special Infected who maintain their original appearance upon death even when on fire.
 * AI-controlled Tanks can scale obstacles impassable for player-controlled Tanks (ie. unmarked climbing areas) which gives AI-controlled Tanks more freedom and advantages than their player-controlled counterparts. An example of this can be seen in the Boathouse Finale, when an AI-controlled Tank arrives at the Boathouse, the often climb onto the upper deck of the house via pulling his entire body up rather than using marked climbing spots.
 * Sometimes, a Tank will spawn outside the safe room in the level The Town. You can see it standing there, but it won't notice you (unless you jump off the church, shoot him, or throw a grenade/molotov at him.
 * As seen in some Beta Gameplay from Left 4 Dead 2 you may not be immediately incapacitated when hit by a car, as Ellis was hit by a Tank-thrown car and only lost some health instead of being incapped.
 * After killing or incapacitating the last survivor on their feet, the Tank will punch the air in victory. (Only visible in third-person.)
 * When you play the Tank in Versus you can see in the First-Person sight that the animation of his arm is different to the Thirt-Person sight. In third person the Tank swings his arm at the Survivor and when they are incapped he forms his hands to fists and beat with both arms on the Survivor. In first-person his arm just moves from right to left in both when the Survivors are standing and when they are incapped.

Survivors
Towering Inferno

- As easy as it sounds. Just throw a Molotov at the Tank when he shows up. - Note: Achievement is also unlocked if you use a gas can.
 * Light a Tank with a Molotov.

Man vs. Tank

- To get this achievement more easily, and without cheats or friends, start up the Boathouse Finale level on Expert. Get into the garage area, kill all of the Infected, and open the door to the street. Fend off the horde and Special Infected, and when it looks clear, kill your team mates. After they're incapacitated or dead, you can change the difficulty to Normal if you like. Normal is preferred because you'll have a better chance of a Tank spawn. Go through the house, and be sure to grab the pain pills before heading into the back yard. Once out there, a Tank should spawn. Take note that if it catches on fire from the nearby fire barrels, the game registers this as damage not done by you and the achievement will not be awarded. You can change the difficulty to easy if you want, but it won't make much difference. Kill the Tank, and the achievement is yours. Another way to obtain this achievement is to speed-run through The Train Station in Blood Harvest on easy. Make sure that you leave the AI players behind. When you get to the railroad bridge, a Tank usually spawns. This is your only chance, kill the Tank before your team gets there and the achievement is yours.
 * Single-handedly kill a Tank.

- Along with Towering Inferno achievement, if you as the Survivor lights the Tank up on fire and nobody else on your team shoots the Tank, the Man vs. Tank will be unlocked as well.

Tankbusters

- This is most easily done in an open area on easy or normal. Sometimes a Tank can get stuck in a window, therefore allowing you to unload into it.
 * Kill a Tank without it dealing any damage to a Survivor.

- Along with Towering Inferno and Man vs. Tank, lighting up a Tank and running away can also ensure that no Survivor takes any damage from the Tank, provided that there is enough running distance and distance between you and the Tank.

Infected
All 4 Dead

- To get this, you only have to have all 4 Survivors incapacitated at once. This counts as death for them since they can't revive themselves. A fast way of doing this is to hit a car at all four of them. If not just take them out one at a time and stay out of the line of fire of the incapacitated ones. Unfortunately, none of your Special Infected buddies can help you either when shooting for this achievement. For example, if a Survivor is being constricted by a Smoker and you as a Tank comes over and incapacitate the Survivor, it will not count towards the All 4 Dead achievement. Another easy way to get this is to have a friend play as the Survivors on the No Mercy level The Sewers. Behind the abandoned restaurant there are several dumpsters. Have your friend, or friends stand behind one of these dumpster with the AI Survivors. Punch the dumpster on to all four of them and it will instantly incapacitate all four if done right. This works well because even if it doesn't, you can still punch another dumpster or car onto the Survivors of the first one. Also, punching them off a cliff will count against the achievement.
 * Kill all four Survivors in one life while playing as a Tank.