Terrain

Terrain features shape every game of Warhammer 40,000, dictating where models can move and what they can see. This page explains how terrain is placed, the categories it falls into, and the four visibility rules (Benefit of Cover, Hidden, Obscuring and Solid) that decide who can shoot whom.

Placing terrain

Before the battle begins, both players furnish the table with terrain features. You can do this in three ways: mark out a defined boundary (a base, tile or mat) and set one or more features wholly inside it; drop a single feature directly onto the table; or arrange two or more features so that together they mark out the edge of an area. Whichever method you use, the patch of battlefield inside that boundary, or covered by that feature, is a terrain area. A mission's deployment map may fix where each terrain area sits and how large it is; if it does not, agree the boundaries with your opponent before the first turn.

Terrain categories

Every terrain feature belongs to one of three categories, and that category governs how it affects movement and sight lines. Note that features sharing a single terrain area can be different categories.

• Exposed offers almost no protection and never slows a model. Craters, razorwire and scattered debris are typical examples.
• Light can grant cover against incoming fire but does nothing to hinder movement or provide lasting shelter. Think barricades, low walls and statuary.
• Dense blocks even the largest war machines and can conceal whole units from view. Buildings, ruins, armoured containers and woods are dense features.

A deployment map may specify which categories should appear in each terrain area. Where it does, place those categories; the map was written with them in mind.

Terrain and movement

Any model can move both horizontally and vertically through Exposed and Light features without penalty. Dense features are more restrictive:

• INFANTRY, BEASTS, SWARM and MOBILE models move horizontally through Dense terrain freely.
• INFANTRY, BEASTS and SWARM models may also move vertically through Dense terrain.
• Any other model can only pass horizontally through Dense terrain where every section its base would cross is 2" or less in height. Where a section is taller, the model must climb it vertically instead. Such models cannot pass through ceilings or floors, and cannot finish a move on any surface above ground level.

Moving vertically to climb up or down a feature carries two conditions: the model must stay within ½" horizontally of that feature, and both the vertical distance up and the vertical distance down are added to the total distance the model's unit has moved this phase.

Models may be set up or finish a move on the ground level of any feature. They can also end above ground level only if the model has the INFANTRY, BEASTS, SWARM, FLY or MONSTER keyword, and after the move it sits stable with no part of its base overhanging the outer edge of that surface.

Terrain and visibility

Four rules determine whether terrain hides a target: Benefit of Cover, Hidden, Obscuring and Solid.

Benefit of Cover

When a ranged attack targets a unit, that unit has the benefit of cover only if every model in it satisfies at least one condition: the model is an INFANTRY, BEASTS or SWARM model standing within a terrain area, or the model is not fully visible to the attacker because of intervening terrain features or obscuring terrain areas. Against a unit with cover, worsen the attack's BS characteristic by 1.

Hidden

A model is Hidden while both apply: it is an INFANTRY, BEASTS or SWARM model within a terrain area that contains at least one Dense feature, and its unit made no ranged attacks during this turn or the previous turn. A Hidden model can only be seen by enemy models within its detection range, which is 15" unless a rule says otherwise.

Obscuring

Terrain areas that hold at least one Light or Dense feature count as obscuring terrain areas. Should every line of sight between two models pass through one or more obscuring areas, setting aside any obscuring area that one or both of those models occupy, the two models cannot see each other.

Solid

Dense features possess the Solid rule, which blocks line of sight through any enclosed gap in the feature's surface sitting no higher than 3" above ground level. This stops models sheltering at ground level from being seen through doors, windows or small gaps, regardless of those openings. Some missions adjust the height at which Solid takes effect.

Models that climb tall features gain superior sight lines and may qualify for the Plunging Fire rule when shooting down at targets below.

Frequently asked questions

What are the terrain categories in Warhammer 40,000 11th edition?

Exposed, Light and Dense, in rising order of how much they interfere with the game. Only Dense terrain ever stops a Vehicle or makes a model Hidden; Light terrain matters purely for sight lines. One terrain area can mix categories, so a ruin footprint with a crater in it is Dense where the walls stand and Exposed where the crater is.

How does the Benefit of Cover work in 40k?

It is a whole-unit test: one model standing clear of terrain and fully visible costs the entire unit its cover. The penalty is applied to the attacker's BS rather than to your save, so it works identically against a 3+ save and a 6+ save, and it does nothing at all against melee attacks or against weapons with [IGNORES COVER].

What is the detection range for a Hidden model in Warhammer 40,000?

15" by default, measured between the two models, so a Hidden unit stays out of sight of anything further away even where a clear sight line exists. Note that a squad which shoots on your turn is visible for the whole of your opponent's turn as well.

Can vehicles and monsters move through Dense terrain in 40k?

Only through sections no taller than 2", and never through a floor or ceiling. A tank can drive over a low wall or a stretch of rubble that happens to be Dense, but a ruin with 3" walls has to be gone around or climbed, and climbing adds every inch of vertical distance to the move. A MONSTER may finish a move on an upper floor; a VEHICLE without FLY may not.

What does the Solid rule do in Warhammer 40,000 11th edition?

It treats the bottom 3" of a Dense feature as if it had no windows or doorways, so a model standing on the ground floor cannot be shot through an opening at that height. Sight lines through gaps higher than 3" still work, which is why a model on an upper floor can be seen while its ground-floor squadmates cannot. Check the mission, since some raise or lower the 3" figure.