Units moving through dense terrain tend to slow down or stop altogether. They may become temporarily lost and need to find their bearings or could be physically slowed down by picking their way through difficult ground full of potholes and tangling vegetation. This means that units sent into some areas are not entirely under the control of the force commander (i.e. you) anymore.
Normal. Standard rules apply, no additional effects on moving troops.
Difficult. A unit of troops that is moving into, out of, or through difficult terrain rolls 2D6 and uses the highest roll as the maximum distance it may move that turn.
If the dice roll is not high enough for the models to move into difficult terrain, place them just inside its edge. Any models in the unit which don't actually move in difficult terrain still get a full 6" move but remember that they must form a continuous chain with the rest of the unit that is in difficult terrain.
Impassable. Can't be moved through at all unless the troops have special training, supernatural abilities and/or the right equipment. Where this is the case it will be noted in the troops' or creatures' description.
Diagram: Difficult Terrain Test. Several Space Marine models are shown moving toward and through a patch of jungle terrain. Models moving entirely through open ground move a full 6". Models moving into the jungle patch are limited by a 2D6 difficult terrain roll (shown as a roll of 3) so only move 3" into the jungle, while the rest of the unit in the open can still move up to 6", forming a chain back to the models in the jungle.