1. Declare Charges
In his own assault phase a player can declare a charge with any of his units that are within Assault range of an enemy unit and not already in close combat. Assault range is typically 6" but some units can assault 9", 12" or more, where this is the case it will be noted in the units' special rules. The unit may charge any enemy unit that can be contacted by at least one of its models making an assault move which avoids any obstructions such as impassable terrain or other enemy units which you do not wish to contact.
A unit that fired in the shooting phase of the current turn may only declare a Charge against the unit it shot at. A unit that remained stationary in the movement phase in order to fire heavy weapons or fire twice with pistols or rapid fire weapons may not charge at all in the assault phase.
A unit may Charge multiple enemy units but only if the charging unit can reach them all without losing unit coherency. Select one unit as the primary target and move to engage that one first as detailed below. If the unit fired in the shooting phase it must start its charge by engaging the unit it shot at first.
Designers Note: The change to having to charge the target of your shooting is an important one, the old assault unit tricks of hitting one unit with ranged attacks and then charging a different enemy can no longer be used (unless you can reach both of course). This helps bring assault units more into line with firepower based ones in that they can only attack one enemy unit in their turn. The one exception to this is units such as Hormagaunts which are both very fast and very numerous as these may be able to engage several enemy units at once, effectively swamping the enemy defence. Also note that a unit doesn't have to charge the nearest enemy unit, although it can be difficult to bypass one unit to reach another as we'll see later.
2. Move Charging Units
Once a model is in base to base contact with an enemy model it is said to be Engaged (as in engaged in combat); the unit that the models belong to is then said to be Locked (as in locked in close combat).
Move all the models in each charging unit before moving on to the next unit. The charging player decides the sequence in which his units will move. All the models in a charging unit make an extra 6" move in exactly the same way as if moving in the movement phase — some units may be able to charge further than this, where this is the case it will be noted in their army list.
Start the charge by moving a single model from the charging unit. The model selected must be the one nearest the enemy being charged. Move the model into contact with the nearest enemy model in the unit being charged — this is the start point of the close combat. Next move each model in the charging unit in turn up to 6" toward the unit or units they have declared a charge on. Remember that if the enemy is not within 6" of at least one model the charge does not happen.
After the first model in the unit has been moved you can move the others in any sequence you desire. There are some constraints on their movement though. The most important one is that each model must end its charge move in coherency with another model in the same unit that has already moved.
If possible the model must contact an enemy model which is not already Engaged in combat. If there are no unengaged models in reach then you must contact an enemy model that is already engaged with one or more friendly models. If you cannot reach any enemy models you must try to move within 2" of one of your own models that is Engaged with an enemy model. If this is impossible then the charging model must just obey the main rule and move to within 2" of a member of its own unit that has already moved.
If you follow this sequence you will end up with all the models in the charging unit in 2" unit coherency distance of one another, having engaged as many enemy models as possible with as many chargers as possible.
In all cases models may not move through friendly or enemy models and may not pass through gaps narrower than their base diameter. You may not move models within 1" of enemy models they are not charging.
Terrain Effects
Models assaulting into, out of or through difficult terrain will be slowed down in the same manner as models moving through it in the movement phase. Roll two D6 and pick the highest to see how far they can move. If their move is insufficient to reach the target unit then the charge does not proceed and no hand to hand combat ensues — the models are not moved and it is assumed they simply did not have time to scramble through the difficult terrain or thought better of it due to their poor progress.
Didn't Make It?
Enemy units that have been charged but have not been contacted are not considered to be Locked and are not involved in the combat in any way.
Designers Note: The rules for charging have been tightened up considerably for the sake of clarity. During the initial charge the attackers are subject to the normal movement rules with the exception that they can now move within 1" of the enemy in order to fight them in close combat. It is possible to set up units to block the path of a charge however since models may still not move through each other. Tight terrain can also mean initial charges become 'choked', although if the combat continues it is assumed to sprawl out as detailed later. Note that difficult terrain is handled differently to the Movement phase, this way we save lots of pointless assault moves which won't result in combats occurring.