You make terrain in an area up to 1 mile square look, sound, smell, and even feel like some other sort of terrain. The terrain's general shape remains the same, however. Open
Fields or a road could be made to resemble a swamp, hill, crevasse, or some other difficult or impassable terrain. A pond can be made to seem like a grassy meadow, a precipice like a gentle slope, or a rock-strewn gully like a wide and smooth road.
Similarly, you can alter the
Appearance of
Structures, or add them where none are present. The spell doesn't disguise, conceal, or add
Creatures.
The
Illusion includes audible, visual, tactile, and olfactory elements, so it can turn clear ground into
Difficult Terrain (or vice versa) or otherwise impede
Movement through the area. Any piece of the illusory terrain (such as a rock or stick) that is removed from the spell's area disappears immediately.
Creatures with
truesight can see through the
Illusion to the terrain's true form, however, all other elements of the
Illusion remain, so while the creature is aware of the illusion's presence, the creature can still physically interact with the
Illusion.