Warhorse

When charging, units entirely made of models with Swiftstride and M 7 or higher roll 3D6, discard the lowest result, and add the result to their M value. When fleeing or pursuing, they roll 3D6, rather than 2D6.

When charging, units entirely made of models with Swiftstride and M 6 or lower roll 2D6, and add the result to their M value. Whenfleeing or pursuing, they roll 3D6, and discard the lowest result.

Swiftstride has no effect on models using a M value lower than 4.

Swiftstride M6 or lower
Charging: M + 2D6
Failed Charge: 2D6
Fleeing/Pursuing: 3D6 (discard the lowest)

Swiftstride M7 or more
Charging: M + 3D6 (discard the lowest)
Failed Charge: 3D6 (discard the lowest)
Fleeing/Pursuing: 3D6

The number of Impact Hits is shown in brackets after the rule. If a creature is granted two sets of Impact Hits, use the highest set, rather than a total, before rolling. If a unit contains more than one model that inflicts a random amount of Impact Hits, always roll separately for each model.

Impact Hits are only made on the turn the model makes a successful charge into close combat, and only against the unit the model has charged. Impact Hits are resolved at the very beginning of the close combat, before challenges are issued and attacks of any other kind are made. They hit a unit in base contact and are randomised as Automatic Hits. If the model is in base contact with more than one unit, randomise the Impact Hits between them as evenly as possible. If the model with Impact Hits is not in base contact with the enemy, no Impact Hits are inflicted.

Impact Hits roll to wound using the S of the model making the Impact Hits. Any armour saves taken are done using the close combat value of the armour, and Parry saves may not be taken. Any Wounds caused by Impact Hits are counted towards combat resolution. 

Unless specified, any rules that apply to the model’s normal attacks do not apply to its Impact Hits.

Vanguard
Fast Cavalry automatically have Vanguard.

Free Reform
Unless it charges, Fast Cavalry is allowed to reform twice during its move without losing any Movement; once before they move, and at the end of their move. The unit may do this even if it marches, provided that no model ends up moving a number of inches higher than double its Movement value.

Fire & Flee
A unit of Fast Cavalry armed with missile weapons can choose Fire and Flee as a charge reaction. If it chooses to do so, the unit will first fire upon the target following the rules for Stand & Shoot. After this, the unit makes a flee move. However, it may not use its Swiftstride if it does so, and the normal -1 To Hit penalty for moving and shooting still applies.

Feigned Flight
A unit of Fast Cavalry that chooses Flee or Fire & Flee as a charge reaction does not cause Panic from fleeing through friendly units and automatically rally in its next Compulsory Movement Phase (unless it is forced to Flee again from another source). In addition, it is then also free to move during the remaining moves part of the Movement phase. The unit is also free to shoot as normal (but always counts as having moved). Note that if the flee move of the Fast Cavalry does not take them beyond the charge reach of their enemies, the unit suffers casualties as normal.

Fire on the March
Fast Cavalry armed with missile weapons are experts at shooting from horseback and can therefore shoot during a turn in which they marched or reformed (providing their weapon doesn't have Move or Fire). However, the normal -1 To Hit penalty for moving and shooting still applies.

Characters
A character model that joins a unit of Fast Cavalry gains Fast Cavalry as long as they stay with the unit. Characters may only join Fast Cavalry with the same Troop Type as them.

Armour Saves
Units containing one or more models with a close combat armour save better than 5+ and/or barding cannot use Fast Cavalry.