
dirgeoverdrive |
"Additionally, while he is within one of his favored terrains, if he gains concealment or total concealment, the miss chance of either type of concealment improves by 10%."
RAW: The %-increase only works in the ranger's favored terrain, but it doesn't seem to require that the concealment come from a terrain effect. So blur in (e.g.) the forest should work.
This is in contrast to the bonus to cover that the ranger(wild shadow) receives: "Whenever a wild shadow is within one of his favored terrains and a feature of that terrain grants him cover..."
The cover bonus explicitly requires that a terrain feature be granting the cover. The concealment bonus does not.