When a unit inflicts wounds they may only affect enemy models in contact with them or within 2" of a model in contact with them. This is effectively the danger zone from which all casualties will be drawn. Otherwise the player suffering the casualties may choose which models die from those in the unit. If the unit has mixed armour types then casualties must be removed from troops with the armour that was used before removing any others. Allocate wounds to one model at a time, each model can absorb wounds equal to their Wound characteristic. Keep allocating wounds to a model until it is dead or all the wounds have been allocated. When a model dies and there are still wounds to be inflicted pick another model and repeat the sequence until all possible casualties have been suffered or the wounds inflicted have all been allocated.
Casualties should be removed in such a way that the unit maintains coherency wherever possible. This represents the way that a unit can be whittled down to a tight knot in close combat.
It is possible that casualties may exceed the number of models in the danger zone, in which case the surplus hits are discarded. The calculation of which models are in the 2" 'danger zone' is made at the start of step 2 (fight close combat) and is not affected by casualties. If a model started a combat in contact with an enemy model that is killed it will be treated as a model Engaged in combat until the end of the assault phase.
If a model becomes a casualty before he has an opportunity to attack then he may not strike back. When striking blows simultaneously you may find it more convenient to resolve one side's attacks and simply lie wounded models on their side to remind you that they are yet to attack back.
Multi-wound Creatures
As noted previously, with multi-wound creatures whole models must be removed as casualties wherever possible.
Different Armour Saves
If the unit being attacked contains models with different armour saves the same procedure is used as for shooting at mixed armour units. So the opposing player rolls to hit and wound for whichever unit he is attacking with as normal. However, when the defending player makes armour saves before removing casualties from a unit with mixed armour saves he uses the best armour saves as long as the models wearing that type of armour are in the majority (ie they outnumber models with worse saves in the unit). Any casualties which are removed after saving throws have been taken must come from amongst the most heavily armoured models first (ie the ones with the best saving throws take the hits).
If heavier armoured models are in the minority use the worse armour saves and take the casualties from the lightly armoured models first. If there are more hits than the majority type, distribute them out so that all go on the majority type before hitting minority models — in each case the differently armoured models get to use their own saves if they are hit. If there is no save type in the majority the owning player gets to decide which group gets hit first.
Example: A squad of Black Templars Space Marines includes four Initiates (Sv3+) and six Neophytes (Sv4+) inside the enemy's 2" kill zone. The squad suffers eight wounds in close combat. There are six models in the unit with a save of 4+ so six armour save rolls are attempted, four fail and four of the Neophytes are removed as casualties; the remaining two hits spill over onto the Initiates and are saved against using their 3+ armour save.
More Attacks Than Models
If the unit has the misfortune to suffer more wounds than it has models in the kill zone then the remaining wounds are 'lapped round' and start hitting the majority type again. For example, if the Black Templars had suffered fourteen wounds, six would go on the Neophytes, four on the Initiates and then the remaining four wounds would be resolved on the Neophytes as they were in the majority. As with all attacks, the results of each Initiative step are resolved before moving on to the next, so the majority type of armour for the unit could change through the phase as casualties occur. For example, the squad above has now been reduced to two Initiates and two Neophytes — if it suffers more wounds in the next Initiative step then they could go to the Initiates or the Neophytes first at the option of the owning player.
Invulnerable Saves
A model may only elect to use its Invulnerable save each time it is allocated a wound under the majority rules given above.
Designers note: This last obscure reference is to prevent individual models with storm shields, rune armour et al taking a disproportionate amount of the damage during close combat, claiming they can break the majority rules or other weirdness.