Here's something that I think there's a lot of confusion about. Part of the problem is that the rules are fairly complicated in the first place. There's also some crucial changes made by the FAQs which, as ever, people simply don't read. Finally, most people have made assumptions (myself included) and are doing it wrong every time until someone tells them different.
I wanted to put together all the wound allocation stuff I could find to try and clear up the issue. This all stemmed from one of the games last Saturday where our opponents were carrying out Look Out, Sir rolls in a different way to what we were used to. Rather than argue too much we let them carry on but I was determined to figure out what the actual rules were when I got home.
Please bear in mind that even though this took a lot of work to piece together, I'm still up for hearing other people's views on it. There are inevitably going to be some parts that are interpretation but sadly that's the way it is with 40K most of the time. I'm sure someone else has done a similar guide to it but this was mostly a learning process for myself as much as anything else.
Forgive me if any of this is patronising but I want to get the basics sorted before we get too technical. As ever with one of my articles, it's going to get pretty wordy in order to be thorough so you might want to grab a cuppa. I apologise for the lack of (much needed) diagrams but it's getting late and I lack the motivation.
Wound Allocation (p.15)
Before I get on to talking about Look Out, Sir itself. I want to cover some of the wound allocation basics that I think people (again myself included) are getting wrong. Ask most people what the big change was with 6th edition and they'd say that it's closest model now which is only the tip of the iceberg!
On the face of it there's nothing to it. Assuming your unit has all of the same saves and the shots are all the same AP value you just grab a bunch of dice, roll the saves and remove a number of models equal to the number of failed saves. Obviously, you're taking multiple wound models into account here so if you fail 5 wounds and the closest model has 3 then he'll be removed and two other single wound models.
Mixed Saves (p.15)
Where the complication comes is where a unit has different saves available to it. For example, a unit of guardsmen being shot by bolters might have half their number in cover and the other half in the open. Assuming you've haven't used Focus Fire (which, by the way, you have to declare BEFORE rolling to hit), you'd need to figure out who was closest and what save they had. For example, if the 4 closest guardsmen are in the open then they're removed before you get to make any cover saves for the next closest.
Crucially, you can keep taking cover saves on that model until he dies. If the next closest model doesn't have a cover save then you keep removing them until you get to the next one in cover or else you run out of wounds to apply.
It's in this way that you can use a model as a tank, something I championed a while ago, which is widely used now. This usually means a 2+ save model leading a unit with 3+ or worse armour. You can keep making 2+ saves on that model all day long provided he's the closest and he doesn't fail any.
Mixed Wounds (p.16)
This whole thing is further complicated by shots with different strengths, AP values or special rules. A great example of this is the new wave serpent which usually has an AP6 scatter laser, AP5 cannon and AP- serpent shield (which has Ignores Cover). Deciding the order you want these wounds to be applied can be a real game changer.
For example, that wave serpent is firing at those poor guardsmen again and wounds will all of its shots. They're mostly in the cover of a ruin but let's say the front 3 models aren't in cover. Clearly you want to use the AP5 cannon shots first as that'll be 3 dead guardsmen. Then you might want to use either the serpent shield shots or the scatter laser shots. The serpent shield will only allow a 5+ armour save whilst the scatter laser allows the full 4+ cover save. If there are some models further back which aren't in cover (unlikely I know) you'll want to use the shield first so that you're making the most of Ignores Cover.
Obviously it gets a bit complicated but you can see how effective use of this rule can be rather than just letting your opponent roll a pile of saves. Bear in mind S8 shots should try to get multi-wound characters so using the bolter fire from a squad to kill the models in front is a good idea. There are a lot of things to think about and a lot of depth to seemingly simple rules.
Random Allocation
This is getting more common with things like vector strike but it isn't a particularly tricky concept. It is, however, an excellent way of bypassing your opponent's plans to tank with a front model so keep an eye out for weapons in your codex that use random allocation.
It's also pretty useful when you can't decide which model is closer. Sometimes it's near impossible to squeeze your tape measure in to figure it out and neither side will want to concede. Most of the time you're better just rolling for it and being at the whim of the dice gods.
Combat Wound Allocation (p.25)
Obviously in combat this process is done at each discrete initiative step. They're still applied to the closest model of course but that's a slightly different bracket now.
A key thing to remember is that a wound must be allocated to a model which is in base contact with the specific attacking model, not just any model that is in base contact with an enemy model.
Contrary to what some people think you can keep applying wounds and making saves on a model before moving onto the next. They don't have to be split up evenly across all models in base contact with an attacking model or models. It's always the controlling player's choice so don't let anyone tell you otherwise.
Also, against what some believe, even models that aren't engaged can be killed. However, it's worth bearing in mind that if they're so far away that they can't make it into the combat when they eventually pile in, they don't actually get to fight and potentially the combat ends. This is, of course, unlikely but it has happened to me once at a tournament.
Look Out, Sir (LOS) (p.16, 26, 39, FAQ)
Crucially, the rules for wound allocation state that you assign wounds to a model and take saves, one at a time. Obviously, this is usually done in handfuls of dice but for LOS it's an important distinction.
First and foremost, to make an LOS attempt there must be models within 6" for both the shooting and assault scenarios. The FAQs have now made it so the closest model to the character is the first to be killed. Again this is something I still see people getting wrong. Before I go any further we should also remember that normal characters need to roll 4+ and independent characters need to roll 2+ to pass an LOS attempt. Don't forget as well that the FAQ changed the wording to remove "unsaved wound" from the LOS description. This is important, as I hope will become clear.
Right, now onto the whole point of this article (finally!). The rules state that for each wound allocated you can attempt to make a LOS "save". Let's assume you're using your two-wound character to tank with a 2+ save at the front of a unit of 3+ save models. You're hit by a heldrake (again not that unusual) who manages to cause 5 wounds. Now, my current way of doing this would be to say, "I'll take two LOS rolls first and then make saves on the character". This is partly done for speed and partly to try and protect your character. You're unlikely to fail 2 out of 3 2+ saves (unless you're me) so you're keeping him relatively safe.
However, if we read the rules explicitly we can actually consider each wound one at a time. So I manage to make three 2+ saves and then fail the fourth. At this point I decide it isn't worth the risk so I declare an LOS roll and pass the wound off to an unsuspecting model near my character. There's nothing to say you actually have to declare how many LOS rolls you'll make straight away. That is, of course, unless I've missed something somewhere.
This is how our opponents were playing it in the last game on Saturday. Granted they did do some other things wrong that we shouldn't have allowed but on this score it seems they were totally right. It may take a bit more time to do and ends up a bit confusing but it's a good way to make the most of your "tank".
The difficulty comes in applying this if your character is the closest model but has the same save as the rest of the unit. In that case you could argue that you'd need to decide how many to LOS before making all of the 3+ saves together. Personally I'd say you could still do them one at a time if your character is the closest model but I'm not totally sure of that. Answers on a postcard.
There also seems to be a belief (and I thought this too) that you can only make a number of LOS rolls equal to the number of other models in the unit. The rules don't seem to say that anywhere I can see though. Only one attempt can be made per wound but it says nothing about a model being used by the character to make multiple successful LOS "saves". Obviously if the model dies you have to move onto another but as long as it survives you can keep passing wounds to the same model.
Other Stuff (p. 33, 35, 43, 63, 64, FAQ)
To finish off here's collection of other things that I found in my search (mostly in the FAQ). Firstly, the gun model in an artillery unit cannot be used to make an LOS attempt.
LOS attempts can still be made on precision shots and precision strikes. This includes Focussed Witchfire too as far as I'm aware. Wounds from a challenge may not be LOS'd (obviously) and again, obviously, can't be used to pass off wounds from Gets Hot.
Another useful thing (perhaps) in the FAQ is that you should remember to keep wounds from a blast weapon in a separate pot to other wounds as they can be allocated to models you can't see, i.e. leave them until last so that you might kill models that the unit's other weapons can't.
Feel No Pain rolls can also be made individually before applying any more wounds to a model.
Finally, something that I don't think many people do (because they see it as complicated), is the weapon range thing. If you've already killed all of the enemy models that are in range of the front firing model in your unit then any excess wounds are lost. Worth bearing in mind.
Conclusion
Some of this stuff could make games a lot more complicated but it helps to know what the rules actually say when someone tries something like this against you in a tournament. This process has certainly helped me understand LOS a lot better and I think it'll be more effective now that I know how to use it correctly.
Once again though, if you disagree and can back it up with rule quotes then please comment. As I say, some of this is open to interpretation and I'm always keen to hear other people's views.