Types of Terrain

Open ground is the default terrain type -- anything not specifically classed as something else. Every rule elsewhere in the book already assumes open terrain, so it needs no further detail here.

Impassable terrain covers anything units physically can't enter, or can't survive entering -- lava fields, deep lakes, chasms. Units can never voluntarily deploy in, enter, move into, or cross impassable terrain; they must go around. A unit can still flee through it, taking Dangerous Terrain tests as it does. Impassable terrain has a Line of Sight value of 5.

A model that marches, charges, flees, overruns, or pursues into or through dangerous terrain must take a Dangerous Terrain test -- roll a D6; on a 2-6 it passes through safely, but on a 1 it suffers a wound with no armour saves allowed.

Cavalry, monstrous cavalry, chariots, and shrines treat any terrain other than open ground as dangerous terrain (representing the risk of riding at speed). A chariot or shrine that fails a Dangerous Terrain test this way suffers D6 Wounds instead of 1.