Any entity may freely Move across a section border with a Height value if the entity is moving in a downward direction. However, doing so results in falling, with the entity suffering #d4 damage where # is equivalent to the Height value crossed.
Some Move entries include a Height value in parentheses, such as Move 1 (Height 2). The Height value provided permits the entity to freely Move across section borders having a Height value equal to or less than the value in the Move entry. An entity that makes such a Move in a downward direction suffers no falling damage. If the Height value of the section border exceeds the Height value in the Move entry, subtract the two and use the resulting number as the # for falling damage. For instance, if an entity moves downward across a Height 3 section border with a Move 1 (Height 2) entry, the entity would suffer 1d4 falling damage.
An entity cannot Move upward if the Height value of the Move entry is less than the Height value of the section border. Move entries that lack Height values, including most base movement, is presumed to have a Height value of 0.
See also: Climbing
Melee and other range 0 Actions cannot cross Height boundaries (unless they have Reach). Ranged Actions can cross Height boundaries. The range of the Action must be equal to or greater than the total change in Height when reaching the target. Additionally, the terrain must not obstruct the entity's ability to see the target. Consider the following examples:
The DM can make exception for special circumstances in which these rules are too simple to accurately model the terrain.
In exploration scenarios, Climbing Obstacles typically have Height values associated with them. This is used to determine the amount of falling damage sustained by an entity playing an Action against the Obstacle if the Obstacle's Reaction takes effect. When attempting to traverse downward, an entity may simply Move as if the Obstacle were not present, but suffers falling damage in the process.