A will-o'-wisp is a CR 2 Tiny undead with AC 19, 22 hit points (27 in 2024), a lightning Shock and one trait that makes it lethal: Consume Life, a bonus action that can kill a living creature at 0 hit points outright on a failed DC 10 Constitution save. It turns invisible, flies 50 feet, drifts through walls and resists most damage. In 2024 its invisibility becomes a bonus action called Vanish, so it can attack and disappear on the same turn.
Tiny undead, chaotic evil
Its Shock is weak: +4 for 9 (2d8) lightning, a 45% hit chance against AC 16, about 4 damage a turn. Its defenses carry the CR. It resists acid, cold, fire, necrotic, thunder and bludgeoning, piercing and slashing damage from nonmagical attacks, and it's immune to lightning, poison and seven conditions, including Grappled, Prone and Restrained.
Variable Illumination lets it shrink or grow its bright light from 5 to 20 feet (plus the same distance of dim light) as a bonus action. Invisibility takes its action and lasts until it attacks, uses Consume Life or loses concentration, so in 2014 it can't turn invisible and Shock on the same turn.
Tiny Undead, Chaotic Evil
| 2014 | 2024 | |
|---|---|---|
| HP | 22 | 27 |
| Speed | Fly 50 ft. (hover), walk 0 ft. | Fly 50 ft. (hover), walk 5 ft. |
| Shock | 9 (2d8), melee spell attack | 11 (2d8 + 2), melee attack |
| Invisibility | Action | Vanish: Bonus Action, ends right after it makes an attack roll or uses Consume Life |
| Light | 5- to 20-foot bright light, adjustable | Fixed 20 feet bright, 20 dim |
| B/P/S resistance | Only from nonmagical attacks | All bludgeoning, piercing and slashing |
| Thunder | Resisted | Not resisted |
| New immunity | — | Petrified |
The swap that matters is Vanish. A 2024 wisp can Shock, then Vanish as a bonus action, and start its next turn Invisible. Its next Shock has Advantage: about 70% to hit AC 16 instead of 45%.
It hunts the dying. Consume Life targets a living creature within 5 feet at 0 hit points. The save is Constitution, which an unconscious character can still attempt. A character with Con +2 fails DC 10 on a 7 or lower, 35% of the time, and dies outright. The wisp regains 10 (3d6) hit points.
The combo that kills downed characters: the wisp Shocks the unconscious character first. Attacks against an Unconscious creature have Advantage, and a hit from within 5 feet is a critical hit, which counts as two failed death saves. Then it uses Consume Life as its bonus action. In 2024 that combo costs it Vanish for the turn; in 2014 it costs nothing.
Work with something stronger. On its own a wisp rarely drops anyone. Pair it with a creature that does, then let the wisp finish them. It flies, so it stays out of reach until someone falls.
Lure with light. It can turn invisible, light and all, and drift through solid objects (taking 1d10 force damage if it ends its turn inside one). A wisp that shows its light 60 feet away, then vanishes and reappears farther off, is a simple way to lead a party off a safe path.
A will-o'-wisp is worth 450 XP. For four characters:
| Party of 4 | Encounter | 2024 difficulty | 2014 difficulty |
|---|---|---|---|
| Level 3 | 1 wisp | Low | Easy |
| Level 3 | 2 wisps | Moderate | Hard |
| Level 3 | 1 wisp + 2 ghouls | Moderate | Deadly |
| Level 4 | 3 wisps | Moderate | Deadly |
2014 labels use the 2014 Dungeon Master's Guide group multiplier, like our encounter calculator. The ghoul pairing is nasty on purpose: ghouls paralyze and drop characters, and the wisp finishes them.
The lantern causeway. A marsh road is marked by lanterns on poles every 100 feet. One of the lights isn't a lantern. It leads travelers off the causeway toward a sinkhole where something bigger waits, and it feeds on whoever goes under.
The collapsed mine. Three miners are trapped, dying, behind a rockfall. Wisps are drifting through the rock toward them. The party has to dig, heal and fight in the dark at the same time.
After the battle. The party is helping the wounded after a skirmish at dusk. Soldiers at 0 hit points are dying one by one, with no mark on them. The healers have a few minutes to find what's moving invisibly between the cots.
CR 2 (450 XP) in both editions. It has AC 19, with 22 hit points in 2014 and 27 in 2024.
As a bonus action, the wisp targets a living creature it can see within 5 feet that has 0 hit points. The target makes a DC 10 Constitution save or dies, and the wisp regains 10 (3d6) hit points.
The 2014 wisp resists bludgeoning, piercing and slashing damage from nonmagical attacks, so magic weapons deal full damage. The 2024 wisp resists bludgeoning, piercing and slashing damage from any source.
Yes. Incorporeal Movement lets it move through creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
Stat blocks: System Reference Document 5.1 (2014) and 5.2.1 (2024), Wizards of the Coast, CC-BY-4.0. Tactics, encounter math and ideas are Loreify's own.
This page includes material from the System Reference Document 5.1 and 5.2.1 by Wizards of the Coast LLC, available under the Creative Commons Attribution 4.0 International License. Loreify is not affiliated with Wizards of the Coast.
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