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Leech, Giant Sea

Small monstrosity, unaligned

Armor Class 16 (natural armor)
Hit Points 16 (3d6 + 6)
Speed 10 ft., swim 30 ft.

14 (+2) 6 (–2) 14 (+2) 1 (–5) 8 (–1) 1 (–5)

Damage Immunities poison
Condition Immunities exhaustion, poisoned
Senses blindsense 60 ft. (blind beyond this radius), passive Perception 9
Challenge 1/2 (100 XP)


  • Amphibious. The giant sea leech can breathe in air or water.
  • Numbing Bite. The giant sea leech secretes a powerful numbing agent when it bites underwater. Its victim must make a successful DC 14 Wisdom saving throw to notice that it has a leech attached unless it is being actively sought.


  • Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 9 (2d6 + 2) piercing damage and the leech is attached to its target.
  • Life Suck. While the leech is attached to a creature and alive, instead of making a Bite attack, it sucks the life essence from its victim. The target loses 1d6 hit points and gains a level of Exhaustion. The leech gains hit points equal to half the loss to the target, increasing its hit point maximum if necessary. A creature can use an action to attempt a DC 13 Strength check to remove the leech. A successful removal causes 3 (1d6) slashing damage to the target, even if the leech is dead. Alternatively, a dead leech can be removed without causing damage with a successful DC 17 Wisdom (Medicine) check.


More dangerous than its freshwater cousins, the giant sea leech is about three feet long. Along with blood, this leech sucks out the very essence of life.

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Tome of Horrors 2020, (C) 2020, Necromancer Games