Up to 1 minute
By gathering threads of shadow material from the Shadowfell, you create a Huge shadowy dragon in an unoccupied space that you can see within range. The illusion lasts for the spell's duration and occupies its space, as if it were a creature. When the illusion appears, any of your enemies that can see it must succeed on a Wis saving throw or become frightened for 1 min. If a frightened creature ends its turn in a location where it doesn't have line of sight to the illusion, it can repeat the saving throw, ending the effect on itself on a success.
As a bonus action, you can move the illusion up to 60'. At any point during its movement, you can cause it to exhale a blast of energy in a 60' cone. When you create the dragon, choose a damage type: acid, cold, fire, lightning, necrotic, or poison. Each creature in the cone must make an Intelligence saving throw, taking 7d6 dmg of the dmg type on a failed save, or 1/2 dmg on success.
The illusion is tangible because of the shadow material used to create it, but attacks miss it automatically. It succeeds all saving throws, and it is immune to all dmg and conditions. A successful Investigation check against your spell save DC and a creature discerns the illusion for what it is.