Dark Visions

You create a vision of a dark horror that takes hold in the mind of a creature that you can see within range. The target must make an Intelligence saving throw. On a failed save, the dark force that is no larger than a 10-foot cube is seen by the target for the duration of the spell. Undead and constructs are immune to this effect. The dark force may take the shape of a creature or tentacles or some other eldritch creation.

The dark horror seems real to the affected target in every way.

The target can use an action to perform an Intelligence (Investigation) check against your spell save DC, ending the effect if the target succeeds.

While affected by the spell the target rationalizes the dark horror in any way. If the creation would damage the target, then the target takes psychic damage from the illusion. Each round the target can take 1d6 psychic damage from the illusion.