Giant Mantis Shrimp

Large beast, unaligned

Armor Class 14 (natural armor)
Hit Points 110 (13d10 + 39)
Speed 15 ft., burrow 15 ft., swim 30 ft.

19 (+4) 12 (+1) 16 (+3) 1 (–5) 12 (+1) 8 (–1)

Skills Intimidation +2, Perception +4, Stealth +4
Senses truesight 60 ft., passive Perception 13
Challenge 5 (1,800 XP)
Proficiency Bonus +3


  • Fluorescing Challenge. The giant mantis shrimp has advantage on Charisma (Intimidation) checks while agitated, as its natural fluorescence flashes in a disorienting array.


  • Multiattack. The giant mantis shrimp makes two Sonic Claw attacks.
  • Sonic Claw. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) piercing damage. The target is grappled (escape DC 14) if it is a Medium or smaller creature and the giant mantis shrimp doesn’t have another creature grappled. Whether or not the attack hits, the target must succeed on a DC 14 Constitution saving throw or take 5 (1d10) thunder damage and be deafened and stunned until the end of its next turn.


  • Water Jet. Each creature within 5 feet of the shrimp must succeed on a DC 14 Dexterity saving throw or be blinded until the start of its next turn. The shrimp then swims up to half its swimming speed without provoking opportunity attacks. The giant crustacean coruscates in richly colored patterns, hinting at additional colors that are indiscernible for most.


Giant mantis shrimps are predatory, carnivorous crustaceans that live in tropical and subtropical seas.

Sonic Assault. Giant mantis shrimps are devasting in close-range combat. Their strikes hit with staggering speed, and even if the initial attack misses, the resulting shock wave created by the assault may finish off a target. The shrimp uses this attack to stun prey before tearing it to shreds and devouring the pieces.

Magical Eyes. These creatures have remarkable vision, able to discern colors and details most other creatures can’t. Between its sonic attack and its vision, the giant mantis shrimp has inspired both engineers and magic users.

Coastal Nightmares. Giant mantis shrimp spell trouble for coastal inhabitants, from clearing out fisheries to destroying piers, levees, and other seaside fortifications.

Though they tend to stay on or near the seafloor, they can pursue fishing boats docking with a fresh haul. Those who have tried to domestic the creatures have met with disastrous ends, as the shrimp destroy their encasements and a swathe of homes or vessels on their way out.


Some giant mantis shrimp wield claws that resemble clubs more than spears. These mantis shrimp are especially devastating to terrain and structures, and are sometimes enchanted to serve deep ones or sahuagin. A siege mantis shrimp gains the following additional trait:

  • Siege Monster. The mantis shrimp deals double damage to objects and structures.

In addition, the giant mantis shrimp has the following action option in place of Multiattack and Sonic Claw:

  • Sonic Smash. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 18 (4d6 + 4) bludgeoning damage. In addition, either nonmagical armor or a nonmagical shield worn or carried by the target (the shrimp’s choice) is partly destroyed and takes a permanent and cumulative ?1 penalty to the AC it offers. Armor reduced to an AC of 10 or a shield that drops to a +0 bonus is destroyed. Whether or not the attack hits, the target and any creature within 5 feet of it, other than the shrimp, must succeed on a DC 14 Constitution saving throw or take 11 (2d10) thunder damage and be deafened and stunned until the end of its next turn.
Section 15: Copyright Notice

Tome of Beasts 3 © 2022 Open Design LLC; Authors: Eytan Bernstein, Celeste Conowitch, Benjamin L. Eastman, Robert Fairbanks, Scott Gable, Basheer Ghouse, Richard Green, Jeremy Hochhalter, Jeff Lee, Christopher Lockey, Sarah Madsen, Ben Mcfarland, Jonathan Miley, Kelly Pawlik, Sebastian Rombach, Chelsea Steverson, Brian Suskind, Mike Welham

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