Ye Olde Shoppe of Magicks – Monster Manuals – Strange Case of Dr. Jekyll and Mr. Hyde

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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.

Strange Case of Dr Jekyll and Mr Hyde
(Monster Tome)

Medium Construct (Shapechanger), chaotic neutral

Armor Class 15 (reinforced leather binding)
Hit Points 95 (11d8+44)
Speed 20 ft., hover 20 ft.

STR 18 (+4) DEX 12 (+1) CON 18 (+4)
INT 14 (+2) WIS 14 (+2) CHA 16 (+3)

Saving Throws Con +6, Wis +4, Cha +5
Skills Medicine +5, Intimidation +5, Arcana +4
Damage Resistances psychic, necrotic; bludgeoning from nonmagical attacks
Damage Immunities poison
Condition Immunities charmed, frightened, poisoned, prone, exhaustion
Senses darkvision 60 ft., passive Perception 14
Languages understands Common; speaks in two alternating voices
Challenge 6 (2,300 XP)

Traits

  • Dual Nature. The tome alternates between Dr. Jekyll Form (rational and defensive, working with the PCs) and Mr. Hyde Form (feral and destructive). At the start of its turn, roll a d6: on a 1–3, it acts as Jekyll; on a 4–6, it becomes Hyde. The tome may also willingly switch as a bonus action.
  • Unstable Essence. Whenever the tome takes more than 20 damage in a single round, it immediately switches forms.
  • Split Consciousness. The tome has advantage on saving throws against being charmed or frightened.

Actions
Dr. Jekyll Form (Controlled)

  • Soothing Words. The tome targets one creature within 30 ft. The creature regains 9 (2d8) hit points, but must make a DC 14 Wisdom saving throw or be charmed until the start of the tome’s next turn.
  • Binding Prescription. Ranged Spell Attack: +5 to hit, range 30 ft., one target. Hit: 13 (3d8) radiant damage, and the target’s movement speed is reduced by 10 ft. until the end of its next turn.

Mr. Hyde Form (Unleashed)

  • Violent Slam. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 18 (3d10+3) bludgeoning damage.
  • Howl of Rage (Recharge 5–6). The tome unleashes a guttural roar. Each creature within 20 ft. must make a DC 15 Wisdom saving throw or take 21 (6d6) psychic damage and become frightened until the end of their next turn.

Reactions

  • Sudden Reversal. When reduced to 0 hit points, the tome instead splits open, transforming into both Jekyll and Hyde specters. Each has 20 hit points and acts independently until destroyed or until 1 minute (10 Rounds) has passed, at which point they merge back into a single destroyed tome.

⚖️ Design Notes

  • A “phase-shifting” fight that keeps the battlefield dynamic.
  • Jekyll provides healing or control, while Hyde goes full offense.
  • The Sudden Reversal gives it a cinematic final act — two smaller foes erupting from one book.

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