Any squad with ranged weapons may opt to lay down suppressive fire. The squad follows all stipulations for overwatch (no moving...), in addition to the following.
*The squad does not need to have LOS to the target, but they must know of its whereabouts (ie target must be at least detected)
*The entire squad must lend suppressive fire to a single target. They can not suppress multiple targets.
*Space Marine combat squads may fire at separate targets, as they are in effect 2 separate units.
EFFECTS OF SUPPRESSIVE FIRE
(NOTE: Suppressive fire is just to keep a squad from advancing. You cannot wound anyone with suppressive fire)
The target of suppressive fire is forced to make a Ld test before he is allowed to move. There is a -1 for every 5 models firing at the target.
If the check is failed, the unit may not advance, and must make a second Ld test. It the second test is failed the unit must seek cover. Any squad under the effects of suppressive fire suffers a -1 to hit from all ranged attacks.
CLOSING
Well, that's what we changed, and it made the game more interesting. It really made those weedy grots into weedy grotz. Not the fearless martyrs that we use them as.