Similar to Squad Mode, Horde Mode occurs when a Horde Leader invokes the primal fury of his followers.

. Starting Cooperation: Horde Leader´s Authority bonus* (see below) + Command modifier (+1 Trained or +2 Command +10% or +3 Command +20%). *Authority bonus (do not use Unnatural modifiers): Fellowship (Dark Eldar & Slaanesh), Intelligence (Tau & Tzeench), Perception (Tyranid), Strength (Orks & Khorne), Toughness (Necrons & Nurgle) or Willpower (Eldar).
. Changing Modes (actions): Enter Horde Mode (must be in Support Range): Full action, Enter Solo Mode: Free action.
. Support Range: Vocal (up to 120m), but inside the Horde.
. Cooperation Damage: -1 Cooperation if Horde Leader suffers 10+ damage from weapons with one or more of the following qualities: Accurate, Blast and Devastating. The cohesion damage can be ignored if the Horde Leader succeeds on an Authority test (free action to be taken as soon damage occurs). Only 1 point can be lost this way per round. Creatures with the Fear Trait (pg. 131) can also cause damage, but also can be negated if Horde Leader succeeds on a new Authority test.
. How a Leader looses Horde Mode: 1) Dying or falling unconscious, 2) Horde´s Cooperation is reduced to zero, 3) When there are no more enemies to kill or the Horde is broke.

Horde Leader Strategies

Each leader may use one strategy per combat.
. Full Offensive: +2 damage for all Horde attacks. Attack/Defense Patterns: Attack!, Charge!, Destroy! Die for Me! & Surround Them!
. Guerrilla: Any mean available to escape. Attack/Defense Patterns: Die for Me!, Fire from Cover!, Hold On!, Keep Together! & Prepare!
. Hold your Ground: +2 APs to the cover used by the Horde. Attack/Defense Patterns: Destroy!, Die for Me!, Fire from Cover!, Hold On! & Prepare!
. Wait for my Command: Re-roll initiative order once/combat. Attack/Defense Patterns: Attack!, Die for Me! Hold On!, Keep Together! & Surround Them!

Horde Attack Patterns & Defensive Stances.Each Horde can only follow one leader, which can take some of the following actions per round, depending on the Strategy used. The Horde must be able to hear and spread those orders.

Attack! (full action, cost: 2 cooperation points): Until the start of the next turn, Horde adds +10 WS and BS.
. Charge! (free action, cost: 1 cooperation point): If the Horde charges and attacks that round it gains +10 to WS.
. Destroy! (half/full action, cost: 3/2 cooperation points): Until the start of the next turn, Horde gains +1d10 of damage.
. Die for Me! (reaction, cost: 2 cooperation points): Instead of parrying or dodging, the leader can make an Authority test to avoid hit, killing a random member of the Horde instead.
. Fire from Cover! (half action, cost: 2 CPs, sustainable): Hordes correctly positioned benefit from cover.
. Hold On (half action, cost: 3 cooperation points): Authority test to heal 1 point of Magnitude/Degree of Success.
. Keep Together! (full action, cost: 2 cooperation points, sustainable): For the rest of the combat, the Horde does not suffer -10 penalty to Willpower tests to resist breaking when below 50% of its starting Magnitude and does not automatically break if below 25%.
. Prepare! (half action, cost: 1 cooperation point, sustainable): The Horde doesn´t suffer the normal -20 to hit when using Suppressing Fire and Overwatch actions.
. Surround Them! (full action, cost: 3 cooperation points): Until the start of your second next turn, the Horde does +1d10 damage on melee, but only if Magnitude is equal or greater than 20 and if there is room to really surround the enemy.

If this is intended for Master and Elite foes, then replace Horde with any other word. Horde has a very specific definition in Deathwatch.

That is exactly the definition I intended to use. Is there anything wrong about it? Because I could change it to... I don´t know... Mob Mode? In my games, I saw how the players explored the Solo/Squad Mode Rules and asked myself: "Why can´t I prepare something similar?" Using the Horde rules I managed to prepare some options on how the horde colud face their enemies, using only one special enemy (Horde Leader) interacting with the Horde.

Imagine one big Ork Warboss surrounded by a furious mob of Ork Boys, why can´t we explore some new rules in order to let the Warboss command his Horde to do some special strategy actions? I´ve tried it already on two game sessions and my players now have a little more respect when fighting Hordes. Remember that before the Errata, it was even easier to crush them.

Any other tips? I´m really interested on what you guys have to say to improve my campaign and (Why not?) the Deathwatch rules.

Apologies. I wasn't trying to discourage you. I had thought that you were trying to have Squad Mode equivalents for bands of Master and Elite opponents. I consider that to be a good thing, I just wouldn't have put the word Horde in there. As for rules for a Master boosting a Horde (also a good idea), I'd just give the Master Special Traits (like a Cohesion pool and few ways to spend it) and try to keep the complexity down.

Thanks for the support, please, no apologies needed. Since english is not my first languade (I´m from Brazil), I´m always afraid that my writting isn´t clear enough, just that. The idea of a trait that can boost Hordes is good, but I really feel that some complexity is needed to create something close to the Squad Mode rules. The Deathwatch is a powerfull opponent already, even the 3 Rank 1 Space Marines that form my gaming group, and I feel there must be something to make the back of their heads itching before they face a Horde with some important leader, or even a group os Master or Elite foes, each with its own hordes. Thanks again!