The Boomer

"They've been calling those Boomers. For obvious reasons."

- Rochelle

"Boomer, don't let it puke on you."

- Zoey

The Boomer is an extremely bloated Special Infected. Its mutation has caused it to produce vast quantities of bile, which it uses as a projectile attack by vomiting. If it hits the Survivors, the bile covers them, temporarily blinding them and attracting the Horde. A powerful but fragile Infected, the Boomer's role in Left 4 Dead and Left 4 Dead 2 is to slow down and sow confusion amongst the Survivors as a group, giving the rest of the Special Infected an opening to eliminate each individually.

Appearance
The Boomer has short black hair and appears in stained sweatpants and a navy sweater which is stretched to breaking point by its vast gut, making it instantly recognizable from a distance. It makes belching and gurgling noises whilst in neutral pose, and groans when it sights a Survivor.

Extent of Mutations
The Boomer has undergone extreme physical and suspected liver/gastrointestinal mutations by an adverse reaction to the Infection. The most notable observation of the Boomer is the extreme bloating of the abdominopelvic cavity. This is thought to have been caused by an abnormal supression of bile inhibition leading to an overproduction of bile. Such overproduction would lead to a build-up in the stomach and cause extreme expansion. However, the normal human stomach alone could not expand to the size required to cause the bloating observed in the Boomer. Therefore it's more likely that the majority of the gastrointestinal tract, bile ducts, and gallbladder have also expanded and contribute to bloating in the abdominal cavity. The tension on the skin from the abnormal expansion has also caused some breakdown in the epidermal and dermal layers causing the skin to deteriorate. In some places the skin has even ruptured exposing some of the bile-filled internal organs. The breakdown of the skin has made the Boomer's increasingly vulnerable to any sort of aggitation. Further, the liquid pressure from the bile build-up far exceeds atmospheric pressure and virtually any puncture causes the Boomer to explode sending bile, blood, and other internal contents of its body everywhere. Other physical mutations observed include massive boil-like growths that appeared upon its skin and face. Whether this is due to overproduction of bile is unknown. Similar to the other Special Infected, it is not distracted by high frequency noises such as pipe bombs or car alarms going off.

The Boomer's bile has a unique chemical binding effect with infected and/or non-infected flesh which produces an extracellular stimulus. This chemical stimulus induces a pheromone-like attraction from nearby common infected which causes them to swarm and attack the bile-saturated source. The exact nature as to why this induces a negative response is unknown but the response is non-discriminatory between infected and non-infected flesh (i.e. using a Boomer bile vial on the Tank triggers the same violent response against the Tank). It should be noted that typically common infected have been known to exhibit an extremely basic form of logic (hence their ability to recognize non-infected). The bile-flesh response seems to trump this logic, which could mean that the stimulus is extremely intoxicating for the common infected.

Left 4 Dead 2
As with all the original Special Infected, the Boomer reappears in Left 4 Dead 2 and has received a slight change of appearance. Its skin tone is more fleshy, it has less hair and has a few more boils. Though when compared to his Left 4 Dead counterpart, he seems more wrinkly and "deflated". The Boomer also has many more details showing the difference in mutation. The greatest change in the Boomer's appearance, however, is the addition of a female counterpart. CEDA has shown some interest in the Boomer. A wall chart detailing its appearance and abilities appears early on in Dead Center, and Infected Hazmat-clad CEDA operatives can be found carrying vials of treated Boomer bile.

Female Boomer
The Female Boomer (or "Boomette") is seen wearing a dark blue or black tank top drenched in bile and blue jean shorts. Unlike the male Boomer, she doesn't have boils or growths. Instead, her skin folds form flaps and perhaps highly Infected forms of tinea on the backs of her legs. The skin on her hands and wrists is black, and looks as if it could be necrosis. Her eyelids and the skin in the area around her eyes are also black. Her teeth seem to be horribly malformed, either meaning she lacked proper dental hygiene before she became Infected, or that the virus or bile can damage the enamel and form cavities. She makes higher-pitched gurgling noises as compared to the male Boomer, and sounds more pig-like. In terms of gameplay, she functions exactly the same to the male Boomer.

Abilities
The Boomer's primary attack is to launch a stream of vomit which can hit multiple Survivors that are close to it. If it is killed it will explode, causing Survivors (and Infected) close to it to stagger and become covered with bile. Survivors hit by Boomer bile will be blinded (losing outlines of their teammates as well) and will instantly attract a Horde to attack them, as well as any individual Common Infected who happen to be in the area. They will glow yellow to teammates and purple to the Infected. Multiple Survivors hit by Boomer bile will not each attract a Horde to them; the one Horde will instead attack all of them. This is also true of Survivors who are covered in bile by the Boomer's death after the Boomer has used its vomit attack; a second Horde will not be attracted until the effect has worn off upon the Survivor's first hit, and until the Boomer itself attacks again. The Boomer may vomit on incapacitated Survivors and on those who have been pinned by other Infected. Boomer bile, at least that issuing from the Boomer itself, has no effect upon other Infected. The Boomer may also claw the Survivors to do 2 points of damage in Versus.

Left 4 Dead 2
Note: Information still needed for some areas.

Survivors
General:
 * Listen for the heavy breathing, gagging and burping sounds.
 * If Boomer is near you and has not vomited on you,shove him back and shoot him.
 * Turn your subtitles on, allowing you to read the Boomer's noises if it is near. This is extremely useful in noisy situations such as the rainstorms during the latter half of Hard Rain or during finales.
 * Keep an eye out for defensive positions. That way you'll be ready if the Boomer blinds you.
 * Avoid being too bunched up with the other Survivors. There's no sense in all four of you getting puked on at once.
 * On Expert, finding and killing the Boomer before it can vomit or explode is incredibly crucial, as the Boomer bile attracts the Horde, which, on Expert difficulty, is much more dangerous than any other.
 * Boomers will often claw Survivors they have vomited on, dealing even more damage. Survivors should be cautious, especially on expert, because it will do 20 damage per hit.
 * The Boomer is probably one of the most difficult Infected to deal with. This is mainly due to the Boomer's ambushing capabilities. They will usually hide around corners or drop down from a high rooftop to "pop" on the Survivors.
 * Take advantage of the fact that Boomers will explode if any part of their body is attacked. Due to their bulk, their arms are often exposed around corners. Just a few rifle blasts could mean the difference between being drenched in puke and escaping unharmed.
 * Never use melee weapons against it if you are shoving it away to shoot it from a farther range.
 * When a Boomer is near, stay away from ledges. The recoil from the explosion WILL push you off. On the up side - the recoil will also stun Common Infected who are located near the Boomer for a moment.

Before bile vomit or Boomer death explosion:
 * If the Boomer is too close, it's a good idea to hit it with your melee attack (which will push it back to some degree), then back away to a safe distance before shooting, or you'll get covered in bile even though you weren't vomited on.Post-75275-1229068253.jpg
 * Caution: You can only safely push a Boomer back about three to four times (if the Boomer has full health).
 * Only if the Boomer is sufficiently far away from both yourself AND all other Survivors should you shoot it.
 * Hiding behind something or running away when it's vomiting makes it harmless for some time and may even force it to rush at you clawing.
 * If the Boomer has vomited on someone and is still close to the bile-covered Survivor, shooting the Boomer and (again) covering the Survivor in bile will not attract an additional Horde.

After being vomited on:
 * Know that a massive Horde will immediately descend upon you (and any others who have been slimed).
 * Hold your fire! Since you can't see, friendly fire is the most likely result. You need to:
 * Run to a defensive position (corners and doorways are particularly good). If there are other Survivors moving, try falling off a ledge so that you'll hang. While this can be very risky, the charging Horde will run off the ledge to their death and deal no damage to you.
 * Crouch! Other Survivors will be able to shoot over you safely if you do so.
 * Use melee continuously to survive the incoming Horde.
 * Once your sight starts to clear, mop up with your weapon.

Helping a slimed Survivor: Survivor Bots' reaction to Boomer:
 * Stay close to the stricken Survivor.
 * Help melee the Horde back or shoot if the blinded Survivor stays safely crouched.
 * Help the stricken player to safely get to a corner or high ground to protect him/her from the Horde.
 * Throw a pipe bomb to distract the Horde; however, if you throw a bile bomb, it will go to waste, as the Survivors covered in bile are primary targets for the Common Infected.
 * Bots will always try to shove Boomers away if they are too close.
 * Bots can shoot like normal even they are slimed.
 * If all human players are outside the vomit and explosion range, let bots take care of Boomers by themselves. They are better at handling Boomers' exploding range.

Infected
While it may be difficult to be completely stealthy as a Boomer, try to hide in shadows, around corners, or within hordes of Common Infected. But be careful: Survivor bots can see you! To ensure that you slime the Survivors, vomit on them at close range, then run up to attack them so that they will be more likely to shoot you. You will explode and spread the bile within a certain radius around you. Once you cover a Survivor in slime, the Survivor(s) will appear with a bright purple outline replacing the original one indicating health status.




 * A very helpful tip, especially when handling rushing Survivors, is to wait for them to come to you. Sometimes it is more effective for you to wait around a corner and let them come into your puking range. This is because there is a delay between a Boomer stopping its movement and puking. Play it safe and let them come to you!
 * To master the Boomer, as with any Special Infected, players must learn the role and spawn patterns for each Infected. In Left 4 Dead, the Boomer will only spawn once per wave of Infected. In Left 4 Dead 2, he/she will spawn even less. When playing as the Boomer, realize that it is a support class - not designed to deal damage directly, but to assist other Infected.
 * Boomers are easily distinguishable from other Infected classes because of their pudgy features. And, given the variety of noises they make, Survivor teams will know when a Boomer is active. Therefore, Boomers should know that spawning and vomiting in rapid succession can lead to a painful experience for the Survivors.
 * Once a Boomer has vomited on the Survivors, whether or not it has actually slimed anyone, there are two options.
 * The kamikaze method is used when a Boomer, after vomiting, runs up as close as it can to the Survivors and begins clawing at them. This puts Survivors at risk if the Boomer explodes. If it does, Boomers can cover any "missed" targets, cover and blind previous victims and cause them to stumble for a brief period. The downside is that this leaves the Infected a man short and, in Left 4 Dead 2, there is no guarantee that a Boomer will reappear next wave. Do note that Survivors know that if they melee the Boomer, it will shuffle back a safe distance and can be shot without sliming any Survivors. If possible, try to weaken yourself so that you can explode quicker than the Survivors will think you will. Another kamikaze strategy is to explode next to another Special Infected after they have attacked and incapacitated a Survivor. This will release the attacking Special Infected, allowing them to attack again before they die, as well as covering the recently incapacitated Survivor with bile. This is particularly useful with Chargers and Hunters, because they can almost instantaneously attack after being knocked free.
 * The alternate method to kamikaze yourself would be to simply flee and let your bile recharge. This allows the Boomer to gain its bile while the Survivors are currently dealing with the panic you previously caused. Some Hordes even last longer than the time it takes the bile to recharge, allowing you to pull off the combos in quick succession and can be used to buy your teammates more time. However, since you are still a part of the field, you will be making a lot a noise, which will keep Survivors aware of your presence. To counteract this, hide in locations they wouldn't expect to see a Boomer or in the Infected-only areas. If you can get enough distance between you and the Survivors, you can get the game to prompt you with the "Press E/X to move closer to the Survivors" message, which will bring you right back to them in Ghost Mode, allowing you to have the perks of respawning without having to die.
 * Yet another kamikaze method is to stand in an area above where the Survivors will pass later. It is possible to puke on them from above, or to jump down into the middle of them and explode. The resulting bile everywhere attracts the horde and makes it easier for other Infected players to deal damage due to the confusion caused.
 * To generate additional Infected, you must either explode on a non-purple Survivor or wait until all Survivors are no longer surrounded by a purple aura and then strike again. Therefore: he who pukes and runs away lives to puke another day.
 * The Hunter can pounce on the Survivor covered in bile to add terrible confusion to the mess; the bile will summon the Infected, who will create a meat shield for the Hunter. By the time the other Survivors are able to get to their pinned friend, it may be too late.
 * However, if the Hunter pounces the only clean Survivor, the others may be too distracted to realize their friend is dying.
 * The Charger, the Smoker, and the Jockey have a pretty nasty effect on bile covered Survivors. Their ability to carry someone away to and from a location can lead to panic when teams try desperately to regroup after being slimed. Also, the group of Common Infected will help damage their victim; perfect for the Smoker and Jockey, who do not deal a lot of damage quickly.
 * If a Boomer and Spitter are on the field at the same time, Infected teams can deal out a lot of damage to the Survivors who cluster close. The Boomer must first summon a wave of Infected on one or more players. Once the Common Infected surround a player, having the Spitter spit on them creates pretty nasty results. Since Survivors can't go through the Infected, they have no choice but to try to clear out while taking the exponential damage from the Spitter's puddle.
 * If The Tank spawns, having a Boomer slime even one Survivor is a huge bonus. The Tank will cause a lot of confusion, but if he is assisted by a wave of regular Infected, the Survivors can get overwhelmed pretty quickly.
 * Unfortunately, there is a delay between the time where a bile attack leaves the Boomer's mouth and before it hits a Survivor. If the Survivor kills the Boomer, the bile will disappear in mid-flight, leaving the Survivor clean.
 * While a Survivor is covered in bile, they cannot see the outlines of the other Survivors (or that of the Hunter, Charger, or Jockey after being pinned). While another Infected is attacking a straggler, take the opportunity to cover the other Survivors with bile. While this may cause the Horde to spread out, it is important to impair the other Survivors' vision so that it becomes more difficult for them to work together and to aim.
 * Most Survivors tend to target the Boomer the instant one is heard or seen. One can hide next to cars with alarms and Witches to trick Survivors into shooting them, triggering the panic event or the Witch.
 * Waiting behind doorways and in small rooms will often guarantee at least one successful slime.
 * If you are outdoors, hide in a place where the Survivors cannot see you and wait for them to be distracted by something else, then run in and vomit (rooftops work well for this).
 * The Boomer should almost always attack an incapacitated Survivor. If you can, try to vomit on downed Survivors so that the Horde comes for them. This makes them almost impossible to rescue, as the sea of zombies will slow down the rescue effort.
 * You can stand on rooftops and vomit down on the Survivors.
 * There is a max distance the vomit can go before disappearing into thin air. If from too high of a vantage point, the barf will never hit Survivors.
 * Don't hide right next to thin walls. Not only can Survivors shoot through most of them, but your ample mass may stick through (due to vector errors), giving them a free kill. The slime from the aftermath will, unfortunately, be unable to get through. Try to hide slightly off the wall to minimize cheap kills.
 * When the Boomer explodes, it knocks everyone back. This includes both Survivors and all Special Infected, even when they are using their special attacks. The good news is that you can knock Survivors off of high places; the bad news is that you can do the same thing to Tanks or other Special Infected.
 * If you have used your Boomer bile and missed a downed Survivor, you can put the Survivors into some extremely sadistic lose-lose situations. If you can, sneak up on a single incapacitated Survivor and simply stand right next to him/her or start clawing them. The incapacitated Survivor cannot do anything about your presence other than shoot you, which will cause him/her to be covered in bile, resulting in swift death. You can also do the same to a pinned Survivor, and if any of his/her friends try to shoot the Hunter or Smoker pinning him/her, they may hit you, causing a similar result.
 * Remember that a Boomer has no pinning attacks, meaning that even with a full team of Infected, you can't all pin a full team of Survivors. You must, instead, try to have your Horde incapacitate at least one Survivor, allowing your Infected allies to sneak in and get all the other Survivors while the single incapacitated Survivor is helplessly pounded by the Horde you summoned.
 * One of the best ways to do lots of damage is to spawn as close as possible to the Survivors as you can. Then jump around a corner once you have a chance to explode on all of them, or vomit and run away.
 * While fires are hazardous to all players, it has a limited amount of usefulness to the Boomer. Depending on the situation, you can intentionally catch yourself on fire and run straight for the Survivors. Since the fire chips away your health, you literally turn into a ticking time bomb. Even if they melee you, you would probably explode before they are able to run a safe distance away. Situations where this tactic can be useful are during a Horde attack, when your teammates are attacking, when you are close to the Survivors and when you are recharging your vomit with no hope of escaping, or if the Survivors decided to use their Molotovs. An added bonus was the fact that the Boomer will be wailing softly in pain, which is noticeably more silent than its gurgling noises, hence a Boomer on fire can often catch Survivors by surprise.
 * If you can, try to get into the crossfire between the Survivors and the Infected to maximize your chance of exploding on them. If you drop down from a roof in between the Survivors and the Infected while they are shooting, they won't have time to stop shooting, and you can explode right in front of them without much risk of melee. Don't be too far away when you explode or you will have wasted your life as a Boomer.

Boomer Tips and Tricks Gameplay
Here is a video with a lot of helpful information and tactics for the Boomer.

http://www.youtube.com/watch?v=rqc6p5KU06E&feature=channel

Achievements

 * See Main Article: Achievements

Behind the Scenes


In the Developer Commentary, it's mentioned that originally the Boomer's explosion simply caused damage to nearby players, and that the Horde-attracting abilities were assigned to the Screamer, another Special Infected that was cut from the final game. When the Screamer was dropped, the screams that formerly attracted the Horde were changed to the Boomer's bile. The Boomer's old explosion behavior can be seen in this video at 1:57:

When the Boomer's bile was first added to the game, it was red. It later was replaced by the green seen in the final version.

In the leaked Half Life 2 Beta files, this can be found: "A bloated, disgusting, fluid-spurting zombie created by a poison headcrab," commenting on the Poison Zombie. Take out the bit about the Headcrab, an alien creature which does not appear in Left 4 Dead, and this effectively describes the Boomer.

Gallery
See image archive for more images...