(thanks to Redemption NL for proposing the seed of this idea) (also, excuse me for any writing mistakes as I am native Spanish speaker)

So, I'm planning on running some Deathwatch scenarios in my club using the miniatures and scenery we have at our disposal, and I thought this could work quite well in adding a bit more tactical depth to combat with Hordes (my players like a lot the tactical aspects of combat and enjoy miniature games, and we do not mind spending a bit extra time for this, so therefore this proposal, as I read some topics where people "complained" that Hordes lasted too little time).

1. Horde structure

Each main Horde in the scenario starts with a Magnitude that is a multiple of 10.

Each Horde is subdivided in sub-Hordes (or mini-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) 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).

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).

Each full 10 points of damage reduce the magnitude of a sub-Horde by 1 (so we'll roll for damage in our group). 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 (i.e, this weapons are very powerful against Hordes and directly damage their Magnitude).

Damage in excess of a sub-Horde Magnitude is not applied to other sub-Hordes (i.e., it is wasted).

3. 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 could be useful to keep track of damage done to a Horde each time a sub-Horde is damaged, so that this check is quicker).

4. Hordes Attacking

Ranged. Each sub-Horde may carry out one ranged attack. It has a to-hit penalty equal to the casualties it has taken.

Melee. Each sub-Horde may carry out one attack against all adjacent enemies, with a maximum of attacks equal to half its Magnitude (rounded down).

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 cannot Aim and they are not affected by ammo expenditute or Jamming.

5. Damage caused by sub-Hordes

sub-Hordes add their Magnitude to their damage rolls.

That's it. I would not use these House Rules when playing in a narrative way as they would add too much complexity, but as I plan on using miniatures, I think the added complexity will be minimum, because it will be easy to keep track of all these things with counters and minis. On the other hand, because all modifiers are equal to the Magnitude of the sub-Horde (or twice the Magnitude) I won't need to lose time referring to the book to see whether to apply a +10, +20 or +30, i.e. the maths will be faster, I hope.

Has anyone done something similar? Do you see any big problems with my proposal?