In my earlier series on undead creatures, I skipped over the will-o’-wisp, the “devil lights” of swamps, marshes and desolate battlefields. In building will-effective o’-wisp encounters, it’s necessary to bear in mind the prime directive of horror: fear of the unknown. To create suspense, it’s best never to name the enemy that the heroes are facing, and to keep them in the dark about what it can do for as long as possible. The No. 1 way to spoil a will-o’-wisp encounter is to tell the players they see will-o’-wisps.
Will-o’-wisps are like fantasy UFOs: they can bob and hover in one place or move up to a zippy 50 feet per round. They’re immune to exhaustion, grappling, paralysis, poison, falling prone, restraint, unconsciousness and lightning damage, and they’re resistant to physical damage from nonmagical weapons along with several types of elemental damage. They have darkvision out to a range of 120 feet but shed their own light out to a range of between 10 and 40 feet, although they can also wink in and out of visibility.
Will-o’-wisps have no physical attack. Their Shock attack is a melee spell attack (Wisdom-based, by mathematical inference), and against unconscious opponents, they can follow it up with the nasty Consume Life feature, which has the potential to kill a player character outright. However, between their many resistances and immunities and their Dexterity of 28, which gives them an armor class of 19, they have nothing to fear from a melee attacker. They’re the rare high-Dex, low-Strength, average-Constitution monster that isn’t a ranged sniper and doesn’t need or even want to be. (more…)