Armor Class 19
Hit Points 22 (9d4)
Speed 0 ft., fly 50 ft. (hover)
Damange Resistances Acid, Cold, Fire, Necrotic, Thunder; Bludgeoning, Piercing, and Slashing from Nonmagical Attacks
Damage Immunities Lightning, Poison
Condition Immunities Exhaustion, Grappled, Paralyzed, Poisoned, Prone, Restrained, Unconscious
Languages The languages it knew in life
Incorporeal Movement The will-o'-wisp stalker can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
Variable Illumination The will-o'-wisp stalker sheds bright light in a 5- to 20-foot radius and dim light for an additional number of feet equal to the chosen radius. The will-o'-wisp stalker can alter the radius as a bonus action.
Ephemeral The will-o'-wisp stalker can’t wear or carry anything.
Consume Life As a bonus action, the will-o'-wisp stalker can target one creature it can see within 5 feet of it that has 0 hit points and is still alive. The target must succeed on a DC 14 Constitution saving throw against this magic or die. If the target dies, the will-o'-wisp stalker regains 10 (3d6) hit points.
Shock Melee Spell Attack: +6 to hit, reach 5 ft., one creature. Hit: 9 (2d8) lightning damage.
Invisibility As a bonus action, the will-o'-wisp stalker and its light magically become invisible. The effect lasts until the will-o'-wisp stalker attacks or uses Consume Life, or until its concentration ends (as if concentrating on a spell).
Shock The will-o'-wisp stalker can cast Shock as an opportunity atack.
Lair and Lair Actions
Stalking Fog The will-o'-wisp stalker’s lair is filled with a 1000 ft cube of dense magical fog 20 feet in height. Creatures within the fog can only see to a distance of 15 ft and no sound travels more than 30 ft. Creatures within the fog may suffer minor auditory and visual hallucinations.
The fog can be dispelled using a Dispel Magic spell or moved with sufficiently powerful air currents. The effect will last up to 1 minute, after which the lair begins to refill with fog.
Culling Fog On initiative count 20 one random creature within the fog may be teleported up to 500 feet in a random direction to an empty space elsewhere within the fog.