Vision and Light

Visibility conditions profoundly affect combat and exploration, determining what creatures can perceive and how effectively they fight.

Bright light — Most creatures see normally in bright light. Sources: sunlight, full daylight, torches within their bright radius, daylight spell, light cantrip.

Dim light — Creates a lightly obscured area. Creatures have disadvantage on Wisdom (Perception) checks that rely on sight. Sources: twilight, dusk, dawn, a full moon, scattered torchlight at the edge of the bright radius, deep shadows, dancing lights.

Darkness — Creates a heavily obscured area. A creature in darkness is effectively blinded when trying to see something in that area. This means automatic failure on sight-based checks. Sources: underground without light, moonless night outdoors, inside darkness spell.

• Lightly obscured (dim light, patchy fog, moderate foliage): Disadvantage on Perception checks relying on sight.
• Heavily obscured (darkness, opaque fog, dense foliage): The creature is effectively blinded — can't see anything in the area.

Darkvision: See in dim light as if bright light, and in darkness as if dim light, within a specified range (typically 60 feet, sometimes 120 feet for Drow). Darkvision is grayscale only — no color perception in darkness. A creature with darkvision in complete darkness still treats it as dim light (lightly obscured), meaning Perception checks based on sight still have disadvantage.

Blindsight: Perceive surroundings without relying on sight within a specific radius. Covers echolocation, heightened senses, or tremorsense. A creature with blindsight can see invisible creatures and is not affected by darkness within its blindsight range.

Truesight: The most powerful vision type. Within its range, a creature can: see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions (and succeed on saves), perceive the original form of a shapechanger or creature transformed by magic, and see into the Ethereal Plane.

• Darkvision does NOT negate the need for light sources entirely — it merely reduces darkness to dim light (with its associated Perception disadvantage).
• Darkness spell creates magical darkness that even darkvision cannot penetrate (only Devil's Sight or truesight works).
• Torches and light cantrips remain valuable even in a party full of darkvision races, because they eliminate dim-light Perception penalties.