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.
Will-o’-Wisp, Advanced
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.
Actions
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.