Unclear swarm rules

[Polkageist]

Whoops! I stand corrected. :)

As far as blocking space, I'm going on the 'diffuse' trait that a swarm has which means that they're not substantial enough to actually block-block movement. You might have to eyeball that one a bit, since you could jump a swarm that's on the ground (ants), and a swarm of flies doesn't really have the mass to stop you barreling through. A swarm of rats or birds though, that might be substantial enough to slow you down by virtue of stepping on rats and having their poor ratty bodies roll around underfoot be difficult terrain.

e: Ah, there it is, pg35 of DF Exploits, swarms and such are automatically evaded when trying to move through their space. Goes both ways I'm sure, so a swarm can 'swarm' past you without slowing down.