This is the latest version we are using with my group when running battles with miniatures. We have already play-tested them quite thoroughly and work quite well. We use mostly AT-43 minis, some Warhammer 40K minis (for the Space Marines) and plenty of d6s of different colors to mark damage on Hordes, damage on cover and other miscellaneous effects.
The rules:
1. Horde structure
Each Horde starts with a Magnitude that is a multiple of 10. Each Horde is subdivided in sub-Hordes of 10 Magnitude each. Each sub-Horde will be represented by one Miniature. Each miniature will have a damage counter (I'll use d6s as we have plenty in my club) to mark how many casualties it has taken.
Each miniature must be a maximum distance of 10 meters from at least one other miniature representing the Horde.
Each sub-Horde may move and use actions as if it was one creature (in this sense, I treat them as a Horde is treated in the Core Rulebook). Whenever they do an action, give each sub-Horde a bonus or penalty equal to its Magnitude (i.e., 1-10) depending on whether big numbers would help or impede such action.
2. Damaging a Horde
A Space Marine attacks a sub-Horde (not the Horde) as if it was a normal creature, gaining a to-hit bonus equal to its Magnitude (i.e., 10 minus the Casualties it has taken).
Damage done to a sub-Horde is calculated in the same way as in the official rules, though it is applied only to a sub-Horde. This reduction will be marked using damage counters near a miniature (as explained above).
Sub-Hordes may be pinned. They gain a bonus to their WP test equal to their Magnitude (i.e., 10 minus the Casualties it has taken).
Other rules for damage (Blast, Explosives, Flame, Psychic) work as in the Core Rules.
Damage in excess of a sub-Horde's Magnitude is not applied to other sub-Hordes (i.e., it is wasted). This means the maximum Magnitude damage with one attack will always be 10, unless the GM decides the attack covers an area big enough to also catch other sub-Hordes.
3. Hordes and Cover
Hordes benefit from cover in the following way:
- The cover value for a Horde is equal to the amount of APs of the cover divided by two (round fractions up).
- For each point of damage to a sub-Horde's Magnitude, roll 1d10. If the result is equal to or less than the cover value, then the hit is cancelled.
- Keep track of damage suffered by cover using d6s (again, use different colors than those used to track damage suffered by sub-Hordes). Cover degrades as per the official rules (though I generally decide beforehand whether a successful hit from a weapon will degrade a particular cover or not to reduce the amount of dice rolling).
4. Breaking a Horde
The rules work as in the Core Rulebook. They apply to a Horde, not to sub-Hordes. This means that a sub-Horde cannot be individually broken, and that it breaks as part of the whole Horde breaking. So, when the Horde's turn comes, you check all Casualties suffered by the sub-Hordes and check to see whether the 25% and 50% values have been reached (in this sense, it is useful to keep track of damage done to a Horde each time a sub-Horde is damaged, so that this check is quicker.
In my club we are using d6s of different colors as they are cheap and easy to come by in boxes of 50 dice. We use two colors, one to mark the overall damage and one to keep track of the damage suffered during a round of combat (and that is changed into dice of the first color after deciding whether to roll for morale of the Horde or not).
5. Hordes Attacking
Ranged
. Each sub-Horde may carry out one ranged attack. It gains a bonus to its BS equal to its Magnitude.
Melee . Each sub-Horde may carry out one melee attack. It gains a bonus to its WS equal to its magnitude. Space Marines can outnumber a sub-Horde only if they are more than its Magnitude; on the other hand, a sub-Horde counts as 1 creature for the purpose of outnumbering Space Marines (meaning you'd need two sub-Hordes to outnumber one Space Marine and get the appropriate bonus to WS).
Damage . Sub-Hordes add their Magnitude to their damage rolls.
Attacks from sub-Hordes may be parried or dodged, but with a penalty equal to twice its Magnitude.
As in the Core Rulebook, sub-Hordes are not affected by ammo expenditure or jamming weapons, but I allow them to aim.
All the above means that the best strategy is to shoot always at "fresh" sub-Hordes as they are a bit easier to hit and more dangerous than damaged sub-Hordes... that's the reason why using d6s for counting damage is enough... Also, when a sub-Horde has taken more than 6 damage I do not attack with it and if two sub-Hordes have been damaged so that their combined Magnitude is 10 or less I use an optional rule in which the two sub-Hordes use a Full Action reforming into one sub-Horde.