Yes I am reusing the picture but it is such a true one that I can't help but use it again to illustrate the beauty of the lasgun. I also need to admit that I am not much of a math hammer guy, its a good basis to start from but I am in the theory hammer camp and it is my way. Now a lot of tactics are out there for the Imperial Guard and focus on the use of units and the more destructive weapons of the IG, however there are few that truly give the angry flashlight the credit it deserves and the many uses for it (warming dinner and sweet rave parties). It is still one of the weakest standard weapons in the game, but it is the core of the IG and will bring you to victory if used astutely. Now obviously orders bring it to a whole new level and I will talk about that, but there is more to this simple laser pointer than just shooting infantry.
First off, this whole article is based off the fact that your IG army has a good amount of infantry, and if you are a guard player there are many other options to play with, but most will have a sizable portion of infantry. My army is all infantry with the exception of two vendettas, and it brings a huge amount of lasgun fire to the table. When using them remember that they are only a part of the whole, you anti-tank and powerful anti-infantry weapons are there to hit at key points, but you are going to be relying on the massed fire to put wounds on most squads. What is critical is to use them to support your over all goals and tactics. This ties into use of orders and doing them in the right order to get the result you desire. So for example a mob of 30 ork boys is in front of your line and for sake of argument is in rapid fire rang, use first rank etc to maximize your shots, this is very effective if you are using veterans especially. You have only one special weapon and no heavy, so thats 24 shots, hit with 12 and wound with 8ish, so you bring the squad down to 23ish depending on rolls. This goes up significantly with veterans btw. Do the same with another squad, to get the into the 15 man range. Then you use mortars, as long as your scatter isn't crazy, you will score enough wounds to bring them below the mob rule threshold and force a leadership and pinning check. With 2 squads and a mortar squad, you a have neutralized a large and dangerous squad, and this is not taking into account heavy or special weapons in the squads. Use your lasgun fire to support heavy weapons that can bring the damage to a critical point. Note that against tougher targets such as space marines, you won't kill as many, but the three marines you do kill will be far bigger difference to that squad.
Also remember to concentrate your fire, don't spread lasgun fire across the board, you have 5+ turns to play, focus on a few squads and maximize your damage on them a turn and then move on once they have been neutralized. This doesn't mean that the unit is dead, but that its threat is now minimal compared to the others around it. Two marines can still be deadly, but focus on the ten man squad instead and save the two guys for later, if you kill them outright good, but don't get tunnel vision on forget what is left in the army to fight. It helps to assign squads areas and units to focus on as well, and if using regular squads, Combining them is recommended, to maximize damage and survivability. 20 guardsmen can make a huge dent in most squads even with lasguns, 50+ shots is hard to argue with. This also maximizes orders as you can spend one instead of two to get the same result. With veterans, their higher ballistic skill makes up for their lack of numbers.
Now another important thing to take into account when using lasguns with heavy and special weapons, is to fire at targets that they can all wound (ideally). Now if you have a lascannon, well your going to fire at a tank but if one is far away and not as much of a threat as the space marine squad thats going to be in charge range next turn, focus on that squad, the lascannon is not wasted as that is a near guaranteed kill. Having a whole squad sit useless when they could be effective is a great way to lose. Remember the heavy and special weapons are there to support the squad, not the other way around. I will talk about MCs later but the basics is to target T6 MCs and lower to at least have a chance of the lasguns wounding. I'm sure I'm not the only one who has had a lone guardsmen take the final wound of a carnifex or other MC and kill the monster. While those are certainly rare, 20+ lasgun shots with a plasma and lascannon can cause a signifcant number of wounds.
So having started talking about MCs lets continue and go into more depth on fight both MCs and Flying MCs. Now there are a lot of really tough monsters out there, but this doesn't mean lasguns are useless. So lets talk about something that is common, fate weaver. I'm sure I am not the only one to face a flying fate weaver with him casting Iron Arm on himself to make him really tough. So the guy has now made the mistake of flying up to your line and thinks because he is flying there is nothing you can do. Wrong, remember a grounding test is incurred on a hit, not a wound. So what lasguns can't wound him, they can still blind the shit out him. This goes for other MCs as well, but use orders to twin link and fire all your las guns at the bastard, this works well with the 20 man blob squad. With all those shots, you will get quite a few 6s. And all he has to do is fail one grounding test. Then he suffers a S9 hit, so now you just turned you lasgun into a lascannon, isn't that a nice trick. Then that lascannon squad you have in your back field and unload with bring it down and hit him at normal BS. You just turned your useless lasguns into a game turning event. This can be effective against other FMCs as well, even better if they are at the T6 threshold, but the key is to not forget about your lasguns, just because they can't wound doesn't mean they are out of the fight and you can save your heavy hitters and maximize the chances of killing him versus watching it fly around and pummel your army.
Now lets talk about enemies in cover. First off you have a great order call fire on my target, which causes the target unit to reroll Successful cover saves. This may not seem like a lot, but that may be the difference between one enemy dieing and three. The more dice your opponent has to roll to pass, the better. Take the example of a scout squad behind an aegis with cloaks, so they have a 3+ cover. Well your squad uses fire on my target and unloads on them. This is very effective against small squads that have a lower cover save than armor. Pathfinder also find this to hurt them a lot. Against these small squads you can maximize your wounds and have a high chance of negating that cover the enemy thought he was safe in. This can give your lasguns an almost ignores cover and is even more hurtful against armies that rely on cover versus armor. Orks, Tyranids, Tau, Eldar, other Guard, this makes your little flashlight useful against those dug in squads. Use this with mortars and you have a deadly combination, the lasguns whittle them down for the mortars killing blow, and if they survive, they will still have to face a morale and pinning check.
Focus fire is related to cover but is worthy of its own section. When targets have different cover saves, use this in combination with orders to maximize damage. Lets say half a marine squad is in cover and the other is in the open, focus fire on them, cause lets be honest one squad is not going to kill a whole squad of marines. They may however kill those five if you pile all the wounds caused by 20 shots onto just those five guys. Occasionally you will have wasted wound or two, but it maximizes the chances of those little flashlights causing the damage needed. This is also a great way to get past a meat shield up front. If he is in cover and the squad or part of the squad behind him isn't you can focus fire to get around the invul or armor save and turn the chance of no wounds to multiple dead enemies. You can also do this by maneuvering your squad to a point where that front man is partially obscured but the majority of the squad isn't, that is all it takes and then you can first rank the crap out of that squad and put all those wounds on the rest without having the storm shield or 2+ save to soak those wounds.
The lasgun is a great weapon when used properly. Though it may be weak, you will have a lot to use. Use them to support the army and give your heavy hitters the chance they need to win. A charging squad supported by lasgun fire can tip the balance of a game to victory. Next to the mortar, the lasgun is your most versatile and effective weapon you have. Let the flashlight party begin!