I may have missed something in the rulebook but how do Mob battles work?

ie: A team of [10 men] local authority enforcers believe/mistake the acoltyes [4 men] as part of a terror cult, and so attack them.

Do I roll all 14 Initative rolls? and work through every single man in combat? or is there a different design for mob combat?

What would happen if a horde of Hormagaunts [60] went into combat with 4 Acolytes do I roll 64 initative rolls? etc

As you can see i'm a little confused.
Thanks in advance.

There are horde rules in Black Crusade and Deathwatch which, of course, are made to overwhelm greater characters thant simple acolytes. So yes, principaly, you roll for all your adversaries. But if you want to create an enjoyable battle, you only roll for what's important, otherwise your fights will be throwing dice and not role playing game in a fight situation.

For a mobs of identical adversaries, I just go with one Initiative roll for all of them; this simplifies combat quite a bit, and can be justified as the group working together as a 'unit'.

If you want to reduce the number of attack rolls you have to make, you can swipe a rule from D&D3Ed and have some of the combatants 'aid' others, essentially using their attacks to add +5% to an ally's chance to hit. So, for a mob of 10 guys, you could say that half are trying to hit the PCs and half are providing Supressing Fire; have 1 guy shoot with 4 guys 'aiding', for a total of +20% (a big deal if firing on Automatic or Semiautomatic), while one guy uses Supressing Fire with 4 'aids'. Thus, you only have to make 2 dice rolls, for a semi-reasonable simulation of a wave of shots.

For 60 horogaunts? I'd use the Deathwatch Horde rules… But a variation on the above could work, too. Since only a few 'gaunts will make in into base-to-base, have one make the attack and the others 'aid'. If your PCs are heavily armoured to the point where they are not intimidated by 'gaunts, you can rule that each 'aid' also adds +1 to damage.

For massive groups like the 60 Hormagaunts, I would split them up into 6 groups of 10, then you only have 6 initiative rolls, plus it's easier to track how many have died or are left. And with the smaller groups, combat squads of 5 or so. When these smaller groups attack, I roll a d10 or whatever (the group size decides the 'd' size) and then the group does that many attacks. Any that don't attack must have been distracted some how, by low flying bullets or mysterious warp fire or as in my group, untied shoelaces.

Adeptus-B said:

I've been using something similar for about a month, now.

I opted for a lower percentage bonus for Mooks, though. Each adversary aiding an attack provides a cumulative +3% bonus to the Attack roll. If they were trained soldiers (Elites, such as members of a Kill Squad, ex-Guardsmen, Storm Troopers from a rival Ordo) I go with the cumulative +5%.

Something else I've ben doing in conjunction with this: to represent the weight of fire (Ranged Attacks) a Mook/Elite adds +3 to the Damage rolled for each adversary aiding in the attack, up to a maximum of +6 Damage. This means a Lasgun can potentially do 10-19 Damage (normally reduced by Armour and TB, say and average total of 6 or 7), so that's roughly 4-15 Wounds. With this House Rule my Players have become quite creative in their use of Cover, and their acquisition and use of Actions and Talents also reflects the potential hazard (Tactical Advance, Hard Target, etc). Getting shot at by eight or ten guns is no walk in the park, and I feel this aptly conveys the sense of danger without being too over-the-top. Nobody just kicks the Xothic Blood Locust nest anymore, that's for sure. At least not without back-up.
Additionally, if the Mooks/Elites were firing to Suppress (which they now do quite often if they have the numbers, usually 3:1 in their favor), I assign a negative modifier to the PCs' WP Tests to avoid Pinning, a cumulative -3% or -5% per aiding adversary, depending on whether it is Mooks or Elites making the attack.

In Melee, as many adversaries can aid an attack as can be Engaged (usually a maximum of 6) and in addition to adding a bonus to hit, each aiding Mook/Elite allows the adversary to add a cumulative +1 to Damage. A Primitive Sword would (normally) do d10+SB; scoring 4-13; and the aid of three others makes that 7-16, meaning that poorly equiped adversaries still have a chance of bringing their opponents down with weight of numbers.

For "Elites" I've also adopted the following: "Fury of the Goon"- weapons normally have a Damage modifier added to the d10 (listed in the profile of the weapon, and usually recorded somewhere conveniently accessible by the GM for easy reference); for Lasguns it's +3, for Melee weapons it would be the SB of the wielder. Using the Deathwatch mechanic for minimum Damage caused by an attack, I track the DoS (just making a quick mental note prior to rolling any Damage, and then if the Mook/Elite rolls a 10 on the Damage die I roll 1d10, and if the number on that die comes up equal or less than the Mook's WS/BS Bonus I exchange the DoS for the Damage modifier. It usually ends up being a measly 3 in 10 chance of causing "Fury of the Goon" (or of the Mook, Thug, whatever), and the extra Damage usually amounts to 3, possibly 4 points at most, but I only use this in situations where the adversaries are backed into a corner (as in trapped with nowhere to run/flee), are fiercely loyal to their employer or cause, and/or are directly commanded by a sufficiently charismatic/fearsome master.

Obviously there are some weapons whose Damage modifier can't be beaten, no matter how lucky an adversary may be (such as the Eviscerator, clocking in at d10+10+SB, Tearing).

We do things a little differently around here with Starting Wounds, Damage mitigation (the spending of Fate Points, Armour, TB, those sort of things), and I pull stuff from all the FFG 40K RPG lines- I have a lightning-quick Gunmetallican Gunslinger with dual .54 Tranter Hand Cannon Legacy Weapons that dish out d10+9, including Mighty Shot, loaded with Man-stoppers; one of the PCs recently pushed open a door, stepped into a darkened room, and got blasted with two of three barrels of a Lathe Boarding Gun ( Hostile Acquisitions , S/3/-, does a d10+5, Pen 1, Scatter) wielded by an ex-Navy Provost (Elite, had 3 DoS at Point-Blank Range)…quite the mess, that one. These examples represent apex participants; they are extremely deadly when provoked. Mooks are not much of a threat, unless they have numerical superiority, so when the PCs walk into an alley and get jumped by a few thugs they shrug 'em off, no problem. However, when they walk into a darkened night club during the early morning hours looking to chat with a local crime boss, and every Mook from the turf is gathered for their morning assignments, the PCs are more likely to talk or bluster (Intimidate), use their Interaction Skills and good role-playing, rather than try impressing someone with a Quick Draw/Hip Shooting combo. Combat (of any kind) in my game is a very messy affair, and the Players avoid it if they can, or play smart if they can't.