We've all seen Saving Private Ryan. Squads are pinned on the beach, a few guys rush forward toward a covered position, and Tom Hanks yells "Suppressing Fire!" Fifteen to twenty guys then light up the target zone with a determined ranged assault.
In Dark Heresy, up to two PCs may assist another in making a Test, and I started thinking about this in terms of the Suppressing Fire Action.
Let's say the PCs need to make a dash forward into an adjoining room or hallway, but they suspect the enemy may be on Overwatch, waiting for them to poke their heads out. One PC can call for Suppressing Fire, and up to two other PCs can assist in this Action. Per RAW, all Suppressing Fire participants must be using a ranged weapon capable of firing Full Auto. Each PC assisting in the Suppressing Fire Action reduces the Difficulty of the BS Test by 1 Level; only one Suppressing Fire BS Test is made (by the PC calling for Suppressing Fire), and this Test is normally a Hard (-20) Test, but with one PC assisting it becomes Difficult (-10), and with two PCs assisting it becomes Challenging (+/-0). Pretty standard, considering the RAW at the top of pg 183, the Dark Heresy Core Rules. Regardless of the number of PCs assisting in Suppressing Fire, no more hits may be scored than the Full Auto limit imposed by the weapon used by the PC (Player) making the Suppressing Fire BS Test.
The Pinning Test is normally Hard, but with one PC assisting it then become a Very Hard (-30) Test, and with two PCs assisting the Test becomes Arduous (-40). Using tens makes the math easy, but perhaps it's a bit harsh; the Pinning Test could go -25/-30 instead.
You run into an issue with Structured Time. Overwatch is an "interrupting" Action, much like Delay. Overwatch would normally "interrupt" Suppressing Fire…but I say let all the bullets fly at the same time, wait till the dust settles, and see who's left standing. I imagine it would make a very dramatic Round.
In the case of conflicting Actions/Initiative Steps, all PCs participating in Suppressing Fire go in the same Turn, and this Turn may be chosen from the Initiative Steps of the Suppressing Fire participants.
Suppressing Fire still requires a Full Action to be used by all participants.
Hmm…needs some work, but it's a start. I'll alert my Players this week and we'll playtest a bit.