The world in COR is divided into three different terrain types—normal, hindering, and hazardous terrain. These different terrain types have different properties, requiring players to constantly take the terrain of the field into account. Terrain is denoted by its mix of colors, so players can easily determine a terrain type simply by glancing at its color.
Normal terrain consists of grass (green), rock (gray), dirt (brown), ash (black), sand (tan), and structural terrain (Structural terrain is anything from wooden floorboards to brick walls; all war machines and upper levels of buildings that appear to be man-made are considered structural terrain). On normal terrain, all standard rules apply. Many normal spaces consist of a mix of two normal terrain types (grass/rock, grass/dirt, ash/dirt, etc.), and a unit occupying one of these spaces is considered to be on both terrain types at once. Some units have abilities that grant them bonuses and penalties on various types of normal terrain.
There are three main types of hindering terrain: snow (white), desert (tan), and shallow water (light blue). Hindering terrain only has a hindering effect if both the base and centered plate on the space are the same color. Students who move out of, onto, or through hindering terrain have their movement reduced by 2 during their unit command (a unit cannot enter hindering terrain if this reduction would make it impossible for them to move into the space). Shallow water is always hindering. Snow is only hindering terrain during night, and desert is only hindering terrain during the day. When these terrains are not hindering, they function like normal terrain. Sometimes units have abilities that grant them immunities to hindering effects.
Hazardous terrain consists of deep water (dark blue) and lava (orange). This terrain cannot be entered unless the unit has an ability that allows him/her to do so. If a unit enters hazardous terrain without such an ability, the unit instantly dies. A unit cannot willingly walk itself into hazardous terrain if such a move would result in death. Even if units have abilities that allow them to ignore the penalties of hazardous terrain, if they end their movement on hazardous terrain then they may not attack or cast spells on targets that are not adjacent to them.
When large units are on multiple different terrain types, the unit is considered to be on all terrain types and suffers all penalties (if applicable).
While the structural part of a building counts as structural terrain, if the actual base of the structure is a color that matches one of the key terrain types, then the base is considered to be that terrain type and not structural. The terrain base is considered to be part of the terrain of the battlefield (in regard to special attacks, environmental conditions, and spells).