Brocken Specter

Spectral Mist. The specter is the center of a cloud of dense mist, in a 120 ft radius sphere. Everything in the mist is Heavily Obscured.

The mist contains a projected shadow for each creature within it, even if there is but one concealed specter. Each shadow appears 60 feet away from their source creature (or at the edge of the mist) as a Large humanoid figure (AC 10), vaguely shaped and wreathed in faint rainbows.

The mist is dispersed (and the shadows vanish, and the specter revealed) if the shadows collectively take at least 10 points of Fire or Thunder damage. Any effect that disperses gas or vapor also disperses the mist.

Shadow Lure. When a creature attempts to Study or Attack a projected shadow, they must first make a DC 13 Wisdom saving throw. If they fail, they must use any remaining movement to approach it, and takes 6 (1d6 + 2) Bludgeoning damage as they stumble.

On a successful save, the creature may attempt a DC 15 Nature check as part of the same action (or gain advantage on the check, if they took the Study action) -- success on this check reveals the radiant mote of the specter, casting the creature's own shadow through the mist. The shadows remain until the mist is dispersed.

Ghost Light. The specter is Invisible and rationalized as a plausible light source within the scene, until it is revealed. Once revealed, the specter sheds its own Dim Light in a 30-foot radius.

The specter is destroyed by magical darkness.

Cast. (while the mist remains) Ranged Attack Roll, 120 ft: +4, reach 5 ft. Hit: 11 (2d8 + 2) Necrotic damage. The attack appears to come from one of the shadows.

Flash. (after being revealed) Melee Attack Roll: +4, reach 5 ft. Hit: 11 (2d8 + 2) Radiant damage. The specter then teleports up to 30 feet away.

Chasing Shadows. When a creature moves (or is moved) toward a shadow, the shadow uses its reaction to move up to 50 feet away. Each projected shadow may use its reaction once per round, and must remain within the mist.