📜 Credit: This monster was originally created by Arnold K. (Goblin Punch). This is a formatted version for easy use in your campaigns.

False Hydra

Large aberration, neutral evil

Armor Class 15 (natural armor)

Hit Points 175 (approximately 100 HP per head)

Speed 5 ft., burrow 40 ft.

STR

17 (+3)

DEX

10 (+0)

CON

18 (+4)

INT

15 (+2)

WIS

14 (+2)

CHA

18 (+4)

Saving Throws Con +8, Wis +6

Damage Resistances psychic

Condition Immunities charmed, frightened

Senses blindsight 60 ft., passive Perception 12

Languages understands Common but cannot speak

Challenge 10 (5,900 XP)

Multiple Heads. The false hydra has 1d4+1 heads. While it has more than one head, it has advantage on saving throws against being blinded, deafened, or stunned.

Blind Song. All hostile creatures that can hear the hydra sing must make a DC 15 Wisdom saving throw at the start of their turn. If the hydra sings with more than one head, all hostile creatures subtract 1d4 from their saving throw. On a failure, the creature forgets the hydra is there and cannot perceive it until the start of their next turn.

Memory Eater. Creatures affected by the Blind Song also forget any victims consumed by the false hydra. Gaps in memory are filled with confabulations - a wife may forget her husband ever existed, believing she has always lived alone.

Actions

Multiattack. The false hydra makes one bite attack and one claw attack per head.

Bite. Melee Weapon Attack: +7 to hit, reach 15 ft., one target. Hit: 14 (2d10 + 3) piercing damage.

Claw. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 12 (2d8 + 3) slashing damage. The false hydra can choose to grapple the target instead of dealing damage (escape DC 15).

Engulf. One Large or smaller creature grappled by the false hydra must succeed on a DC 18 Dexterity saving throw or be swallowed. A swallowed creature is blinded and restrained, has total cover against attacks outside the hydra, and takes 11 (2d10) acid damage at the start of each of the hydra's turns.

Running the False Hydra

The false hydra is not just a combat encounter - it's a psychological horror experience. This creature works best when you build suspense over multiple sessions before the reveal.

Signs of Infestation

Empty houses with meals still on tables
Townspeople who can't explain why they're crying
Extra place settings at dinner for "no one"
Notes written in handwriting no one recognizes
Animals that panic for seemingly no reason
Photos or portraits with people cut out or painted over

DM Tips

Build the mystery slowly. Have players make Wisdom saves periodically. On failures, describe scenes where they clearly saw something horrifying - but then immediately forget what it was. Pass notes to individual players about things only they notice.

Use the party against itself. If one player makes their save and another doesn't, the first player sees the hydra while the second sees nothing. This creates incredible tension.

The reveal is everything. When the party finally breaks free of the song (perhaps by going deaf, using Silence, or destroying enough heads), they suddenly remember EVERYTHING - all the people who died, all the horror they witnessed and forgot.