http://www.3plusplus.net/2012/11/controlling-what-your-opponent-removes/

Something we have alluded to a lot and discussed obliquely has been how mobility impacts your shooting in 6th. Not only do the concepts of 5th edition transfer over to a certain extent (and this is true really of any gaming system which we shall discuss briefly) but the way models are removed is now a huge component of how shooting and mobility interact. Let's look at the basic concepts first...

Movement means your guns will be in range. With the changes to Rapid Fire and the addition of Snap Fire for Heavy Weapons (not to mention each model moves individually within a unit now) being able to move and shoot is much more viable. Even walking units with bolters or lasguns are able to reach out to an effective 30" each turn for damage. Whilst a lot of weapons in 40k have a pretty extreme range (say compared to Warmachine/Hordes), a wide amount of weapons are more effective at a closer range (i.e. 12-18" or even closer). Not to mention this brings the concept of combat into play and whilst it may play second fiddle to shooting, it's still something you cannot just ignore. If armies always sat at 48", we'd see the armies with the most/best weapons at such ranges always winning and this is certainly not the case. Mobility enacts certain weapons for shooting.

Furthermore, movement means your guns can see. This will go hand in hand with what we discuss later for the changes in 6th but without the ability to move and shoot, hiding is pretty easy. A lot of discussion has happened around the Internet over the past years in terrain setup and how one can never really hide anything during the game because of an opponent's ability to angle shots (i.e. deploying in the corners; flanking via movement, etc.) and the ability to move around terrain. This is essentially true (assuming terrain doesn't line of sight block from three cardinal directions) but it obviously forces an opponent to move differently to engage you. As the game wears on and there are less units and more terrain (vehicle wrecks), the concept of completely hiding becomes more possible. This also depends on an opponent's ability to move and shoot – if an opponent is static they only have one way to engage a hidden opponent through deployment. This means an opponent has a much greater scope of hiding specific units or even entire parts of their army based solely on terrain.

This application of this is pretty basic – if you can move and shoot, your opponent has a much harder time hiding significant portions of their army. The faster you can move and shoot, the harder this is and the more able your army is to engage the enemy.

So what does this mean in direct relation to 6th edition and the changes brought on by it? Simply: the player doing the shooting has the most direct control over what models are removed. Why? Because they are the ones moving and then shooting. This is simplified in the extreme but that's the gist of it. No longer can you just remove what models you want or allocate wounds where you want, it's now based on models which are closest to the firing unit and can be seen. This means the placement of the firing unit (which is done through....movement) is very important and dictates the majority of model removal.

There are several mitigating factors we need to identify here – many of which can be controlled on both sides but in the end, the final say is given to the shooting player because they get to make the final move with their models before shooting begins. The only exception to this is when a vehicle is wrecked and the controlling player gets to place the squad inside anywhere within 6" of the transport access points. This will generally happen after the movement of the opposing player's army (rare exceptions are shooting actions made during movement phase; tanks ramming each other, etc.) and thus they are not able to see where the enemy unit is/how it is arranged and therefore identify the best way to engage it through their movement. Beyond this though, the final movement phase before you begin shooting as the offensive player, will dictate the order of model removal. Let's look at the mitigating factors.

1)      Look Out Sir! – this can obviously fob wounds off onto other models within the unit. Not hugely reliable with just a upgrade character but a fully-fledged character with multiple wounds can prove frustrating here

2)      LoS blocking – where one cannot see, one cannot remove models; this is a two-way street but again the final say is given to the offensive player in that given turn – in the previous turn the opposing player may look to hide their unit or specific models and thus make it harder for that unit/models to be targeted but the offensive player in the next turn has the opportunity to respond to this movement (this might put that unit in a poor location but there is still the option to counter this movement, etc.); the offensive player is also capable of positioning their unit to utilise LoS blocking terrain pieces/vehicle hulls to essentially snipe part of the enemy unit – this is a great way to circumvent tanking characters or snipe out special weapon models, etc.

3)      Model placement – the placement of models within a unit is obviously a very important factor in relation to which ones are removed first; this is again reduced in effectiveness by being mobile and being able to flank a unit but if you can't do this, well your opponent chooses the order the models are removed essentially. Otherwise your opponent may be able to limit this (i.e. in the centre of a circle) but never completely stop you from being able to snipe – particularly when this is combined with above factors.

And this is really the entire point of this – if you lack mobility, your opponent has more control over the game. If you have mobility, you're taking some of that control back. Know this. Use this.