(Lightbringer @ Jun. 21 2007,14:20)
QUOTE
A newly mindless swarm will have 0 BMs (as they are all removed when the swarm becomes mindless) - this means that this swarm is better if assaulted than it was when it was 1BM short of being mindless or will be when it has 1 BM over being mindless (for assault resolution modifiers).
First off, "mindless" is being changed, just the word, to "instinctive" to better represent what's going on.
This is actually the intended effect: as soon as a formation goes "instinctive", they hunker down and stick together, waiting to be reconnected.
In 40k, when Tyranids are out of Synapse range, one of their options is "Lurk", which, in addition to other things, gives them +1 to their cover saves... I don't want to mod that into the rule, so the benefit of having no Blast markers is given instead. If they continue to get shot up, then things get worse for them.
They are *NOT* broken, so don't think of it that way, think of them more as "cut off from command".