Illusions: distinguish sensory detail from substance

SRD 5.2.1 · Magic

At the table

1. Read the originating effect for the senses or mental faculties it affects.
2. An illusion manifesting in space is insubstantial and weightless.
3. Unless the effect says otherwise, it appears affected by its environment, such as visual shadows or audible echoes.

Example decision

A visual illusion of a person stands in sunlight and appears to cast a shadow. Does the shadow alone establish that the person is physically real?

No; a visual illusion can appear with shadows under this rule.

The general entry specifically gives shadows and reflections as examples of how a visual illusion appears to interact with its environment. Those appearances do not make the illusion substantial. Use the specific spell or effect to decide how interaction or examination can reveal it and what senses it can deceive.

Watch for this mistake

Do not invent a universal detection check from this glossary entry. Its environmental examples are not a replacement for the discovery procedure of the specific illusion effect.

Ask the table

Which senses does this illusion affect, and what does its own text say reveals it?

Source rule

Spells and other effects sometimes create magical illusions. Such an effect defines what the illusion does and which senses or mental faculties it deceives. If an illusion manifests in space, the illusion is insubstantial and weightless, yet it seems to be affected by the environment as if the illusion were real unless the effect that created it specifies otherwise. For example, a visual illusion of a creature casts shadows and reflections, and wind appears to affect the illusory creature. Similarly, an audible illusion echoes in an echoey space.

Source: SRD 5.2.1, 183. Online guide.