A sinister, urban predator, this particular mimic understands most other creatures fear the dark. So, it becomes a beacon they will come close to avoid it before first extinguishing the life and then its prey's life. No one knows the origins of this particular breed only that it has accounted for dozens of victims. This isn't because of its ambush tactics, but also because it can easily switch spots with a benign street lamp, baffling those trying to defend themselves.

Vapor Mimic

Large monstrosity (shapechanger), neutral

Armor Class 12 (natural armor)

Hit Points 127 (15d10 + 45)

Speed 15 ft

Str 18 Dex 12 Con 16 Int 5 Wis 14 Cha 13

Skills Stealth +7

Damage Resistances fire, poison

Damage Immunities acid

Condition Immunities prone

Sensesdarkvision 60 ft, passive Perception 12

Languages -

Challenge 5 (1,800 XP)

Shapechanger.

The mimic can use its action to polymorph into a street lamp or back into its true, amorphous form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Adhesive (Object Form Only).

The mimic adheres to anything that touches it. A Huge or smaller creature adhered to the mimic is also grappled by it (escape DC 15). Ability checks made to escape this grapple have disadvantage.

Alien Sight.

Magical darkness doesn't impede the mimic's darkvision.

False Appearance (Object Form Only).

While the mimic remains motionless, it is indistinguishable from an ordinary street lamp.

Grappler.

The mimic has advantage on attack rolls against any creature grappled by it.

Marching Order (Object Form Only).

A creature playing the bagpipe mimic in its instrument form is immune to fear and has immunity to sonic damage as long as they continue to play. As long as the creature continues to play it may grant a number of creatures equal to its Charisma bonus (minimum 1) advantage on saves versus fear.

Actions

Multiattack. The mimic makes a pseudopod and bite attack.

Pseudopod.

Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 9 (1d10 + 4) bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait.

Bite.

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 9 (1d10 + 4) piercing damage plus 9 (2d8) acid damage.

Fumes.

The mimic expels toxic fumes in a 20ft radius. All creatures within the area of effect must succeed on a DC 14 Constitution save or be Poisoned for the next minute. At the end of each turn, the creature may repeat this save with the effect ending on success.

Slight of Pseudopod.

If the mimic is unseen by any creature, it may magically change places with another street lamp within 30ft.

Bonus Actions

When the Lights Go Down (Object Form Only).

The mimic dims the light it produces as well as all other light sources in 90ft, magical or otherwise. This can move the area into magical darkness. All creatures with an intelligence of 4 or great must succeed on a DC 13 Wisdom save or be Frightened for the next minute and move in a random direction each time they Move. This blind panic state lasts for 1 minute, until a creature succeeds when repeating this save at the ends of its turns, or the illumination is restored.