Javellin Gunner

**Javellin Gunner (in abbreviation, jav)** is a skill-based MOS who is useful in almost every difficulty. Skill-based means his damage doesn't come from shooting bullets as rifleman, but instead comes from aim and use his skill properly. He can deal huge single-skill damage to T1/T2 threatens or deal massive aoe damage to T3 hordes from far distances(with the help of vision). He also has the unique skill in this game to produce explosive charges(ECs) and claymores from nothing. If the time permit, he could possibly produce as many ECs as he can, as well as claymores. There is no game that can't win with infinite number of ECs. Furthermore, he could also save teammates/himself by placing paralysis trap in mid-to-late game.

The only mode that jav will be having a trouble with is pmc/pmc+ with outbreak or not. The reason is pmc biological units(except pmc tank, pmc walker, pmc helicopter, pmc battle walker) will try to dodge HE/AT rockets by moving away from the red dot, as well as attacking claymore and try to trigger an explosive charge(EC) placed by players. That doesn't mean jav can't do anything to pmc. His rockets will force the pmc biological units to "dance", i.e., to move away from the aiming red point, not shooting or using their skills. Therefore, he provides a crowd control just like combat engineer's barricade. By aiming at pmc but not actually using his rockets again and again, he can continuously force pmc to move the place he want, and let his teammates deal with the rest of job(kill pmc). However, when it comes to pmc T1/pmc+ T1, jav is quite useful again.

The reason why jav can be called a carry mos in difficult mode such as multiplayer survival/Nightmare with T1 modifier is

1. He doesn't need many level to deal decent damage to T1s. With level 4 AT rockets, he is able to melt down any T1s within 3 shoot of rockets. The only exception in early games would be Grotesque(which is the job of bullet MOS, like SFAAT, autorifleman). If there is one, try leave it to SFAAT or kite for bullet MOS.
2. He doesn't need many items to deal decent damage, unlike bullet MOS like rifleman, autorifleman, etc., who may need Aim Assist, Armor Penetrating bullets, and a GOOD gun. The only item that would greatly enhance his damage is proper vision and energy replenish.
3. He can stack ECs(with level 2 javelin skill) by putting an EC then Z+X to disarm it. This enables the team and everyone to not worrying about searching and stacking EC for late game bosses like Darreus or Cacumen. Therefore, the team can use EC to deal with early game T1 threats. As well as having much more ECs for Cacumen than a game without jav.

Therefore, he is able to deal higher damage than bullet MOS in early games and carry the team's level up faster. Such that in mid-to-late games, bullets MOS like autorifleman, rifleman, etc will be able to deal constant damage with the support of vision, items and proper kiting(which is also a job of jav). Nevertheless, his damage doesn't scale better with the time of the game never mean he is useless in late games, giving that he is producing EC 24/7 and his already good enough damage with 4 level AT rockets and 4 level javelin skills.

## Basic tips

#### Why do I pick jav/ What is the job of jav(In Insane- Modes, without T1 modifiers)

1. To clean T3 zombies regularly with HE rockets(especially in outbreak modifiers), and to clean T2/T1 zombies in early games with AT rockets in relatively shorter time than other MOS.
2. To give far distance fire support. With the help of vision or teammates information, jav can kill instant threats such as spitters/lacerti in very long distance.
3. Produce ECs so that the team can deal with T1 threats more easily, such as the Arachtnids in escorting CLP Mission, or the Minerva in escoring mayor mission. As well as making a trap for Cacumen.

#### What is the playstyle I should take?

For beginners, it is recommended to solo away from the team at the start of game, such as wandering around the lake in the middle of map. It is recommended to find a place away from mission or team and try to block all the zombies spawn in that place. The reason is simple and straight:

1. Less zombies will chase your teammates. It increase the survival chance of the rest of the team. Unless the teammates has good skill to kill them and are begging you not to take all exp for yourself.
2. Not staying with mission objectives doesn't mean you are not helping mission. The zombies are spawned randomly around the map (outbreak zombies spawn randomly around players, mission T1 zombies randomly spawn at the edge of the map). If a jav can successfully block the zombies spawn in an area of the map, the people doing mission will have less threats. However, when no other people are doing mission or the mission objective is near you, try to do the mission or find another place to block the zombies.
3. To reduce the chance of teamkilling.
4. It is always easier to kill hordes of zombies when you are sure that they will chase you. A sudden appearance of a teammate will disturb their behaviour and making using rockets more difficult.
5. A jav is able to deal with 99% things by its own. Not many MOS can do this. For example, bullets MOS will have difficulties dealing with hordes of T3s and if the hordes can't be cleaned in time, farther zombies will not chase you and go into your teammates. Also if the hordes are not killed in time such that the number of T3 zombies reached maximum in a game, no more hordes will spawn, which means less exp more spawn for players and less level.

To block zombies, it requires

1. NOT die. If you die, all zombies flow into your teammates and you will need a revive. It is not only something bad for yourself, but also something even worse for your teammate, if you had half of the map zombies chasing you. So keeping alive is the most important thing to the TEAM. Even though the zombies chasing you are not killed in time, don't risk to trade your life for them.
2. Find a good place. The place you are kiting and soloing can be close or not close to the mission, but it should never be in the middle of the path where the mission objective is going. For example, in blaad escorting mission, it is good to kite first at the right hand side of blaad to block all the spawns from the right half side of the map. For another example, if the Combat Medic is going to revive someone at tcp3 from city, it is good to kite below the triangle spot near RA facility and cliff. In easy times, the lake/swamp in the middle of the map is an good option, due to it's plain land and provide good plain vision without many trees, and almost 1/3 to 1/2 of the zombies will chase to you(or say, be blocked).
3. Take the aggro of zombies on yourself, i.e., make sure that every newly spawn zombies (T1/T2) around you will chase you. If you lost their aggro on you, it's better to report the team what kind of zombie it is and where it is going.

However, it doesn't mean that you should solo all the game and run away from your teammates. But it is recommended to do so when the game is safe, saying that you have teammates staying with mission objective and you don't have many teammates dying, because it is the best way to practice your skill and contribute to the team. In anyway, a jav should NEVER stay in Thalim for no good reason:)

#### What SI(Skill Identifiers) should I take?

The best combinations in e.g. hard ob is WK+EN. When no mod is picked, it is hard to level up. Therefore WK+AR is picked over WK+EN to fast level up and help teammates level up. If there is no early threats in the game, WK+EN can also be picked. When T1 modifier is picked(in multiplayer game), WK+AR will lead to less remake of the game, though you need to rely on your teams and your luck to find more energy cell or a kinetic integrator in late game, otherwise you have to use your mana carefully.

1. Whiz Kid(WK) in 99% of the time is a must taken SI for jav, because it increases the damage of HE rockets, AT rockets and explosive charges by 30%. With WK, a full level AT rockets can deal insane 7500x130%=9750 damage. Even though it is not full leveled up, 30% more damage usually means you will need 1 less AT rocket to get a T1 threat down, which also means you can kill a T1 threat 55s in advance.(55s is the cd of 1 level AT rocket) This is a huge advantage. It also means lvl1 HE rockets will deal 1300 damage instead of 1000 damage, and therefore is able to kill spitters with 1040hp in hard difficulty to 1200hp in nightmare difficulty. It also means lvl4 HE rockets will deal 2860 damage instead of 2200 damage, and therefore is able to kill hunters with 2470 hp in hard difficulty, to 2850 hp in nightmare difficulty.
2. EN/PU is needed for mana regeneration. A jav with constantly producing ECs and using rockets will never have enough mana even with EN and item kinetic integrator. Mana control is a crucial part for a good jav since jav's damage come from spending mana. Using skills wisely is an active way to do this, while taking proper SIs is the passive way to achieve this. PU is picked over EN only when there's other carry MOS and you don't need to use rockets so often or need to share energy cells.
3. AR. A good talent to level up first when you need to carry the team's level using level 3 AT rockets or you want to produce ECs since the very beginning.
4. SS. In rare situations when no quick clot has been found and you are going to die. Learn 1 lvl soldier skill and SS can save your life.
5. HA. In pmc modes to survive a grenade from pmc.
6. LA, TT. In nightmare+ modes to outrun from T1s.
7. Other SI are neither useless(such as VT, RF) since jav is not a bullet-based MOS, or neither inferior than the SIs above(such as IT inferior than EN).

#### What skill points should I learn?

In hard/insane outbreak(which is the best mode to practice), the best skill points is (given proper SI taken and no need to learn self aid)

1. lvl1 HE rocket
2. lvl1 Javelin skill (for increasing the range of HE rocket)
3. lvl1 AT rocket or lvl2 Javelin skill (if team needs more damage against early gourmads, pick AT rocket, otherwise learn javelin skill and start producing EC)
4. lvl2 AT rocket or lvl3 Javelin skill (same as above, lvl3 Javelin skill is for more energy production and therefore can produce EC constantly)
5. 6. 7. 8. spend skill points to get full level AT rockets and lvl3 Javelin skill

9. lvl4 Javelin skill(to reduce the cost and cd of rockets further, but mostly importantly to unlock paralysis trap). Paralysis trap can help teammate and yourself in difficult situations and also trigger explosive charges(to kill hunters for example) if other rockets are on cooldown. Same reason can also lead to an earlier pick of lvl4 Javelin skill before level9.

From lvl10. If mana regeneration is not a problem(e.g. you have kinetic integrator), fully upgrade HE rocket is recommended for more damage. Otherwise, if survival chance is a problem(need self aid or more move speed or rifle butt), soldier skill is in prior.

A good jav(with some luck that you have zombie fans) should reach lvl4 at end of Prologue, lvl8 at escorting CLP mission, lvl 10 at end of Chapter 1 and lvl13 at end of chapter 2. Failing to do so in hard/insane outbreak indicates that your teammates are carrying you and you should try find and kill more zombies.

In nightmare outbreak/hard no mod/insane no mod, more HE rockets can be learned earlier in order to one shot killed the unburried or gluttons. However, this will delay your pace of leveling up AT rockets and lead to difficulties in killing T1. So it's recommended only when the teams has few AOE skills and are good at compensating single target damage.

In T1 modifiers, lvl1 HE rocket should be skipped and must be skipped. There are some players who like taking HE rocket to kill T3 hordes to level up faster. However, it levels up faster towards level 2,3,4 but will levels up later to the full power of killing T1s, saying that lvl4 AT rocket and lvl4 javelin skill at lvl8. Because 1 skill point is wasted and you are always 1 level behind the maximum build-up. It is easy to compensate one level in early games by killing hordes, however, exp difference between lvls are bigger at bigger levels, and in T1 mod there are less exp to farm than other mods. Therefore, it is not recommended to learn HE rocket before lvl8 unless spitters are urgent to be killed and AT rockets are on cd.

In PMC no mod/outbreak, there is no much difference between different ways of learning skill points. Because javs are only picked for fun in these modes.

#### What items do I need?

The prior item for jav is energy cells or kinetic integrator(KI) for constantly using skills and producing ECs. If someone wants kinetic integrator from you, trade him with your ECs, since you need it for the only permanent thing that can be stacked forever in this game. However, in easier difficulties, such as hard+outbreak, there is no such urgent to overkill your enemies, therefore KI can be shared to satisfy the mental health of other energy-abusing players.

The second and probably the last thing jav would need or would like to have is bunch of ground flares/flare guns. Vision is crucial to use rockets and therefore kill T1s from far distance before they reach to you or your teammates. It is also very useful even when your rockets are on CD or you can't kill T1 in 1 rocket, because you will need plan your kiting route according to the direction where zombies come from. As well as planning how to use rockets. For example, if you want to use AT rocket on a cursed, but you just see 3 spitters coming towards you, you would need to use that AT rockets to spitters or your rocket will on cd when they reach you. You will also need vision to know that they spawned and take their aggro, so that they are not leaked from your duty to your teammates.

There is no special guns needed for jav, since he doesn't rely on it to do damage. Therefore the best gun for jav would instead be focusing on increasing the survival chance of him. In terms of that, MP75R is recommended for new players who have difficulties outrunning hunters or minerva. Once you have the skill to outrun them, MP75R provides negligible bonus. Then US-MCR is in overall the best weapon for jav, since in this case jav will have little difficulty dealing with flyers, swamers, thredders, pooches, those small hp but fast move speed zombies. US-MCR provides +40% attack speed roughly and is specialized in killing those zombies, with a little trade-off in move speed. SOF-AR, Styner BR-2 provides higher damage but also less move speed, which has more cons than pros. HK42 is also useless. M5-MAR is useful against emergency situations but jav don't need more MGLs in most cases, and therefore should be left first to teammates like Combat Medic who need it most.

Generally good consumables such as quick clot, first aid kit, MGL, grenades, are useful but only for emergency situations.

Other permanent items such as aim assist, kevlar body armor, should be left first to the people who need it more, such as VT automatic rifleman.

#### How to prevent teamkill?

As many new-to-intermediate players might meet this situation, preventing teamkill is crucial to javelin since he can kill teammates in various ways. And there's no excuse for that. In other words, unless someone intentionally want to be teamkilled(such as someone waiting for you to use rockets, and when you do so, he deliberately jump to the behind of you), it is ALWAYS a jav's responsibility if teamkill happened. It not only kills teammates, but also drains all the mana of jav, making this MOS 99% useless except being a moving barricade. Therefore, a good jav should always try to prevent teamkill when using rockets:

1. Solo and keep a big distance from your teammates.
2. If you are alone need to give long range rocket support to your teammates, always check your team positions before you rocket(join fireteams, alt+S or manually clicking the button if no vision)
3. If you are not alone and you might blackblast your teammates, go to the edge of terrain and make sure behind you is a wall or cliff. If the team move in a squad, you should be the kiter and use rocket at same time. Therefore no teamkill will happen if you kite. If you are not the kiter (say there is a FSS wants to kite), jav should always be the person who stand at the edge of a squad team(if no nearby cliff is found). This is VERY IMPORTANT in multiplayer T1 modifiers.

#### How should I use HE rockets?

HE rockets have larger aoe area but deals far less damage than AT rockets. Therefore, HE rockets should be used on T3 hordes at most of time. However, in these situations it can or should be used on T2/T1 threats:

1. There's a need to reduce the T2/T1 zombies' hp asap, such as defilers, hunters, lacertis, usually with the help of another DPS MOS. Or in other words, if someone would die due to lack of 1k dmg on T1.
2. Low hp T2/T1s like spitters, hunters, bruchus which HE rockets can kill them in 1 shot(with enough HE rocket lvl).
3. There's enough mana to waste, which never happens in difficult modes.
4. There's as much T1s as T3s, e.g., 10 gourmads squeezed together, with Immussilus on their heads, and hunters between gourmads.

However, it needs experience when HE rockets are used on high-hp T1s, such as gourmads, gargantuan. Take Gargantuan for example, in hard difficulties, gargantuan has 16000\*1.3=20800hp, while 1 shot lvl4 AT rockets with WK has 7500\*1.3=9750 damage. After you use 2 AT rockets on a gargantuan, it left with 1300hp, which is the damage of lvl1 HE rocket. Given that gargantuan will regenerates some hp, you can kill a gargantuan with 3 AT rockets or 2 AT rockets + 1 HE rockets + some auto attack. For gourmads, it has 18500\*1.3=24050hp, with or without an additional HE rocket, you will have to use 3 AT rockets to take it down anyway, therefore it's not necessary to use HE for bonus damage and waste mana.

In summary, HE rockets should be focused on T3 hordes such as drakes, unburried, risens, etc.

#### How should I use AT rockets?

AT rockets are high-damage rockets but has less aoe area. 1lvl AT rockets requires 110 mana and have a cooldown of 55s. While full level AT rockets(8 kill points for AT rockets and javelin skill) requires 90mana and have a cooldown of 20s. Missing an AT rocket means a waste of mana and time, and is especially unacceptable in early game. Therefore, aiming AT rockets is a basic skill to become a good jav. This requires the player to do these things as accurate as possible:

1. A prediction of zombies/PMCs move. The player needs to be clear where those zombies/PMCs are going and who are they chasing. As well as a proper vision/information from teammates about the current position of zombies/PMC if it is a long-range shoot. It also depends on the move speed of enemy.
2. A calculation of casting time. This slightly depends on the level of AT rockets (the more lvl it is learned, the faster it is casted). But in overall, it is about 1s for all level AT rockets.
3. A calculation of flying time of the rocket. This is determined by two factors: how far this rockets gonna fly and how fast it fly. It needs a lot of practices to get familiar with the flying time of different distances. Whether javelin skill level 2 is learned is also an important factor to take into account. It increases the flying time of a lvl4 AT rocket to the maximum casting range from 5s to 3s(i.e., without lvl2 javelin skill, it takes 5s+1s casting time to fly over 70 range, otherwise it takes 3s+1s).

If all things are done perfectly, we would want this equality to satisfy:

The time of zombies going to the casting point from currect position = The casting time of rockets + The flyting time of the rockets from your position to casting point

Last but not least, there is no doubt that AT rockets should be used on T1/T2 threats first. Especially, AT rockets are among the few resorts to deal with zombies/pmc which have ranged attack and can make deaths at far range, such as PMC walkers/PMC tanks/vesania/ignis. However, when energy permits and there is no better ways to deal with T3 (such as HE rockets on cooldown or HE rockets can't kill T3s like glutton), and you don't expect to use another AT rockets in the future cooldown time (from 55s to 20s), AT rockets can be used on T3 zombies which may lead to deaths, such as commandos/lickers.

#### How should I use Q skill (placing an EC)?

There are two ways to use Q skill:

1. To produce an EC and disarm it and save it for the future. The combination hotkeys are Q+Z+X. It can be used for make a trap for high threaten T1 such as cacumen, or for being given to teammates who need more instant damage such as combat medic, or use it by yourself.
2. To use it right now.

#### When should I use EC right now?

EC can be casted on the ground by pressing "Q", or by being collected around the map/cache. It should be kept in your items until you know what enemies these ECs are against. Putting ECs randomly on the map, hoping it would be useful at some time, is not realistic. Not to mention that some zombies like boomer, spitters will cause explosion upon death and trigger the EC, and PMC will try to trigger EC when possible. Therefore it's clear that ECs should be better used against high-threat enemies in the clear future:

1. As dealing direct damage towards enemies. If the need to kill T1/T2/T3s as soon as possible outweighs the need to save an EC for the future, such as saving your teammates.
2. As a better way to kill low-hp T1/T2 hordes. If 6 hunters and 2 lacertis are grouped together, while AT rockets have not enough aoe range to kill all of them, and HE rockets have not enough damage, an explosive charge can do this job perfectly.

#### How should I use W skill (Paralysis trap)?

There are two ways to use W skill (Paralysis trap):

1. As a temporary barricade (combat engineer's skill). It is used to save yourself/teammates/mission objectives by placing W away from the people in danger and attracts zombies towards the Paralysis trap.
2. As a way to trigger explosive charge. It is often used with an EC to kill hunter squads or lacertis.
3. As a way to push players/zombies. Everying will be pushed backward when Paralysis trap is killed to death (by either player or zombie or pmc) or after a short period of time if no one attack the trap. It can be used to change the position of mission objectives or citizens or police officers. It can also be used when being chased by a cacumen, by placing a trap between you and cacumen. In this case, Cacumen will attack this trap and kill it by 1 hit, and you will be pushed forward while cacumen will be pushed backward.

## Advanced tips

#### Why do I pick jav/ What is the job and playstyle of jav (in higher difficulties such as Nightmare, or with T1 modifiers)

1. Carry the level of key teammates who are weak in early game but stronger in late game. To do so, jav need to carry his own level as well. This can be done by picking Always Ready SI or solo away from teammates for a period of time. In higher difficulties, it is recommended to call your DPS friend to stay with you in safe place and level up with you.
2. Produce ECs.
3. Block zombies in a certain area of map is crucial in nightmare T1. If there are other kiters are picked for the main camping team, jav should try to block tcp3 or tcp4 alone and change his place accordingly to the mission. If no other kiters are picked for the main camping team, jav should be the kiter for DPS MOS.

#### How to prevent screenshaking from rockets?

When rockets are aimed too close to players, the players will have screenshaking when rockets exploded. This usually happens when jav is trying to rockets the zombies chasing him. In the screenshaking time, the player will not able to move jav to the desired place and can be dangerous in this time. Therefore, it is crucial to cultivate the habit to use shift command: "shift + Move to a place" when casting a rocket near yourself. It has two functions:

1. It eliminates the after-casting time. The jav will move immediately after using rockets, instead of waiting for a tiny but not negligible time then start to move, comparing to the usual way: cast a rocket and click move to a place immediately after casting.
2. It prevents/reduce the mistake caused by screenshaking.

#### How to rocket enemies very close to me but not killing myself?

This is crucial especially when jav is chased by fast move speed zombies and is able to kill them with only 1 rocket, such as hunters/flys/pooches. The usual way is stop and click/press rocket hotkey, then find a place to rocket, according to the rocket AOE indicator. It can make mistakes during the short time when you are finding a very close place to rocket, which includes all the fast move zombies but not yourself. Therefore, it is recommended to cultivate the habit to use this command:

1. First, decide a direction which you are moving to and issue the move command to jav for a longer distance.
2. Second, press rocket hotkey and find a rocket place **BEFORE** jav move to that position and stop. This place should ideally include your jav at first time. Once it is decided, hold the position of mouse.
3. Finally, wait for jav to run out of the already-designated rocket red circle, i.e., wait for the color of jav to be not red. And left click mouse and release the rocket.

It is often combined with shift commands above. The full command for a rocket shot should be " move + Z + T (stop sprinting) + find and fix place to rocket + cast rocket + shift + move + Z + T (start sprinting)". It is notable that, if shift sprinting trick is used, it is possible to use rocket at the edge of rocket circle, and run out of the circle while the missile is flying in the air.

#### What are the other use of rockets?

1. In PMC modes, rockets (both HE and AT) will force pmc biological units to move from the aiming red point. Therefore, you can use rockets to force them move to the desired place(either farther away from you, or force them to come to you)
2. Rockets will provide a short period of time vision on the aiming point (about 6s). When energy permit, HE rockets can be used into the trail chasing you and get a temporary vision, in order to get more zombie information and kill some spitters if you are lucky.

#### How should I use claymore?

Claymore deals negligible damage to zombies, comparing to other rockets and EC. As well as it can hardly kill pmc due to pmc's explosive resistance and pmc's intention to destroy claymores. Therefore, it is not worth to use 70 mana to deal direct damage. However, in rare situations, claymore can do the unique job which is irreplaceable in this game. That is to say, claymores should only be used as a trigger for ECs. It can be useful in these situations:

1. Place EC and claymore for specific high threat enemy. E.g. for undead ignis/vesania in T1 modes or survival modes, if other resorts like AT, HE rockets are hard to aim or hard to kill, EC + Paralysis trap can be dangerous. In this case, with the help of vision/Team Leader mark, jav can place EC + claymore and run, and trigger the trap to kill them remotely and safely. (Besides this, in ua3, pmc snipers are difficult to kill in nightmare difficulty and love chapter, so sometimes it needs jav to put around 20 ECs to fill the graveyard and trigger them by claymore or any other ways.)
2. Place EC and claymore for enemies that would spawn in fixed positions. Such as the "unknown engine" in the "Destroy origin of electromagnetic field" mission, or Buck Deny in PMC+ modes, or even the random tychus spawn in game.

#### How to put many ECs instantly?

This trick is needed when multiple ECs are needed to kill a high hp zombies. Click/Press shortkey on item and then on the ground for multiple times would take a long time, long enough that it can be dangerous for zombies like Cacumen to give a hug on you. Therefore, to put many ECs at once is a crucial skill for not only jav, but all MOS that would possibly use ECs.

1. Select a place, noted as A, near the place where you want to place the ECs, noted as B. You should be able to place EC at point B if you are at point A.
2. Move to A and hold shift, then click on EC, then left click on place B for multiple times. You need to click fast enough and finish this process before you really move to point A. Otherwise, you will stop placing EC when you reach point A.

#### Should I use smoke?

Smoke consumes a lot of mana (75) and deals no damage. The aim of smoke is to reduce the move speed of zombies and increase the survive chance, or to reduce the vision/range of pmcs. For the first case, it consumes more mana than another more powerful skill, Paralysis trap, which cost only 60 mana. For the second case, it is less powerful than using rockets to force pmc move. Therefore, smoke grenade should only be used in rare situations:

1. Paralysis trap is not learned or on cooldown. And there is urgent need to slow zombies like Cacumen, otherwise someone would die.
2. Another kiter is kiting and in danger, and Paralysis trap would ruin the aggro of zombies, and a smoker grenade can save the kiter's life.

Anyway, it is better to save this 75 mana and transfer it into damage or paralysis trap.

#### How to save mana/maximize my damage?

Firstly, they are the same thing. One should never save mana by just afk and regenerates mana. It did regenerates mana though, but that is not a skill a player would like to learn. Neither does using energy cell or picking up a KI. Saving mana refers to use the minimum mana to get maximum damage, or in other words, use rockets wisely, so that you don't need to use more rockets to compensate for your mistake. Furthermore, a jav is weak when rockets are on cooldown. If you can kill something using 1 rockets, you'd better not use 2. Therefore, you would need to:

1. Not just kite zombies but gather them. The HE rocket aoe has a circle shape, a good jav should try to kite and let T3 zombies to fill in all your HE circle. AT rockets has small but not tiny area. With proper kiting, it is possible to kill 4 hunters, 4 spitters or 4 gourmads in one shot. And it is great improvement from hitting 2 T1s to hitting 3 T1s (50% more damage), or from 3 T1s to 4 T1s (33% more damage). When it is not urgent to kill down the zombies chasing you, you can choose a T1/T2/T3 hordes in good shape even though they are far away from you. Needless to say, this requires a lot of practices. But once it is done, a jav can be able to block any threats away from yourself and your teammates.
2. Save HE rockets if you know more T3 zombies will spawn soon. In outbreak mode, T3 hordes spawn at a specific second in the timer, for a frequency of once per minute. That is to say, hordes can spawn at 13:20, 14:20, 15:20 etc. or 13:50, 14:50, 15:50 etc. This specific second is fixed in every chapter and differs from game to game, depending on the cutscene time and the time when first player pick his MOS. Only when the number of zombies reaches a maximum threshold in the map, this mechanism will stop. This threshold is about 250 for hard ob, 300 for nightmare ob. Therefore, if you are just a few seconds ahead from the next spawning time, you can choose wait and kill more T3s in one HE rocket.
3. Save AT rockets if you know more T1/T2 will spawn soon and you are safe at the moment. Usually, T1/T2 spawns with the mission (unless in T1 modifiers). For example, if you are chased by only 1 gourmad, it is better to save the AT rockets and wait for other T1/T2 to join with gourmad, unless you are sure that before next AT rocket cooldown is ready, there's unlikely to be new T1/T2s.
4. Get familiar with the number of AT/HE rockets/EC you would need to kill every T1/T2s. If you are going to use that number of AT rockets on them, sooner or later, then don't waste more ammo or EC or HE rockets on them.