Ye Olde Shoppe of Magicks – Monster Manuals – The Hungry Caterpillar

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In keeping with the Haunted Mansion our party is currently exploring, I came up with a WHOLE haunted library ala Gomez Addams

Encounter Mechanics

  • The books remain inert until one is pulled from the shelf. When disturbed, all awaken.
  • They can hover off the ground, flapping like birds. Some have the ability to run.
  • Their CR can be set between 2–3 each (slightly weaker alone, but dangerous as a group).
  • The fight can escalate as more books fall open—giving your party a frantic “stop pulling tomes!” realization.

Encounter Notes

  • Trigger: The fight begins when one book is pulled from the shelf. The rest join after 1 round, 1d4 books at a time, for rising tension.
  • Tactics: Books hover and swarm. “Art of War” boosts the others, “Odyssey” disrupts positioning, “Dracula” heals mid-fight.
  • Party Balance: Facing all 8 at once could overwhelm — consider staggering their arrival for a cinematic escalation.

The Hungry Caterpillar
(Monster Tome)

Medium Construct, chaotic evil

Armor Class 13
(hardbound resilience)
Hit Points 75 (10d10+20)
Speed 20 ft., hover 20 ft.

STR 12 (+1) DEX 14 (+2) CON 15 (+2)
INT 10 (+0) WIS 12 (+1) CHA 14 (+2)

Saving Throws Dex +4, Con +4
Skills Perception +3, Stealth +4
Damage Resistances bludgeoning, piercing, slashing from nonmagical attacks
Damage Immunities psychic, poison
Condition Immunities charmed, frightened, poisoned, prone, exhaustion
Senses darkvision 60 ft., passive Perception 13
Languages understands Common, Sylvan; cannot speak
Challenge 5 (1,800 XP)

Traits

  • Spectral Hunger. The Hungry Caterpillar does not need to breathe or eat, but its spectral manifestations crave endlessly. Whenever it reduces a creature to 0 hit points, it regains 10 hit points.
  • Creeping Whispers. While within 30 ft. of the tome, creatures hear faint rhymes and nursery lines in their minds. At the start of their turn, they must succeed on a DC 13 Wisdom saving throw or be frightened until the start of their next turn.
  • Illusory Fruit. Once per short rest, the tome can conjure an illusory banquet within 15 ft. that lures creatures. Any creature that sees it must succeed on a DC 14 Wisdom saving throw or be charmed and move toward the fruit on its next turn.

Actions

  • Bite of the Caterpillar. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 13 (3d6+3) piercing damage.
  • Spectral Caterpillar (Recharge 5–6). The tome projects a ghostly caterpillar that snakes through the battlefield. It targets one creature within 30 ft.; that creature must make a DC 14 Constitution saving throw. On a failure, the caterpillar burrows through their body, dealing 21 (6d6) necrotic damage and reducing the target’s Strength by 1d4 until the end of their next turn. On a success, the creature takes half damage and no Strength reduction.
  • Metamorphosis (1/day). If reduced below 25 hit points, the tome transforms into a horrific spectral butterfly. In this form, it gains a flying speed of 60 ft., resistance to all damage except force and radiant, and the book form vanishes and it loses all previous actions but gains the following:

Spectral Butterfly (Metamorphosis Form)

Armor Class 13 (spectral resilience)
Hit Points 25
Speed Flying 60 ft.

STR 12 (+1) DEX 14 (+2) CON 15 (+2)
INT 10 (+0) WIS 12 (+1) CHA 14 (+2)

Saving Throws Dex +4, Con +4
Skills Perception +3, Stealth +4
Damage Resistances all except Force and Radiant
Damage Immunities psychic, poison
Condition Immunities charmed, frightened, poisoned, prone, exhaustion
Senses darkvision 60 ft., passive Perception 13
Languages understands Common, Sylvan; cannot speak
Challenge 5 (1,800 XP)

New Attacks & Abilities

  • Wing Slash. Melee Weapon Attack: +6 to hit, reach 10 ft., one target.
    Hit: 15 (3d8+2) slashing damage as razor-sharp spectral wings cut through the air.
  • Glittering Dust Cloud (Recharge 5–6).
    The butterfly flutters its wings, releasing a shimmering cloud in a 20 ft. radius. Each creature in the area must succeed on a DC 15 Constitution saving throw or take 18 (4d8) necrotic damage and be blinded until the end of their next turn. On a success, they take half damage and are not blinded.
  • Ethereal Dive.
    The butterfly dives toward one creature within 30 ft. The target must make a DC 15 Dexterity saving throw. On a failed save, the target takes 21 (6d6) force damage and is knocked prone as ghostly wings pass through their body. On a success, the target takes half damage and remains standing.
  • Soul Nectar (1/day).
    As a bonus action, the butterfly absorbs life force from the battlefield. Each living creature within 15 ft. must succeed on a DC 14 Constitution saving throw or take 9 (2d8) necrotic damage. The butterfly regains hit points equal to the total damage dealt.

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