Will-o’-wisps are malevolent, wispy balls of light that haunt lonely places and battlefields, bound by dark fate or dark magic, to feed on fear and despair.
Tiny undead, chaotic evil
Armor Class 19
Hit Points 63 (14d4 + 28)
Speed 0 ft., fly 50 ft. (hover)
Abilities Str 1 (-5), Dex 28 (+9), Con 14 (+2), Int 17 (+3), Wis 18 (+4), Cha 12 (+1)
Saving Throws Dex +12, Con +5, Wis +7
Damage Immunities lightning, poison
Damage Resistances acid, cold, fire, necrotic, thunder; bludgeoning, piercing, and slashing from nonmagical attacks
Condition Immunites exhaustion, grappled, paralyzed, poisoned, prone, restrained, unconscious
Senses darkvision 120 ft., passive Perception 14
Languages the languages it knew in life
Challenge 8 (3,900)
Consume Life. As a bonus action, the will-o’-wisp 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 13 Constitution saving throw against this magic or die. If the target dies, the will-o’-wisp regains 10 (3d6) hit points.
Limited Magic Immunity. The will-o’-wisp can’t be affected or detected by spells of 6th-level or lower unless it wishes to be. It has advantage on saving throws against all other spells and magical effects.
Ephemeral. The will-o’-wisp can’t wear or carry anything.
Incorporeal Movement. The will-o’-wisp 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 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 can alter the radius as a bonus action.
Multiattack. The will-o’-wisp makes two shock attacks.
Shock. Melee Spell Attack: +7 to hit, reach 5 ft., one creature. Hit: 18 (6d8) lightning damage and the target must make a DC 13 Constitution saving throw. On a failed saving throw, the creature is stunned until the start of the will-o’-wisp’s next turn.
Invisibility. The will-o’-wisp and its light magically become invisible until it attacks or uses its Consume Life, or until its concentration ends (as if concentrating on a spell).
The advanced will-o’-wisp is featured in the Heart of the Iron God adventure.