Amphibious. The crab can breathe air and water.
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Claw (Melee Weapon Attack): +15 to hit, reach 10 ft., one target.
Hit: 30 (4d10 + 8) bludgeoning damage. -
Mandible (Melee Weapon Attack): +13 to hit, reach 5 ft., one target.
Hit: 25 (3d8 + 7) piercing damage. -
Tail Slam (Melee Weapon Attack): +18 to hit, reach 15 ft., one target.
Hit: 35 (4d12 + 8) bludgeoning damage.
On a hit, the target must succeed on a DC 25 Strength saving throw or be knocked prone. -
Crushing Grip (Recharge 5-6): The Giant Crab attempts to squeeze its opponent in its massive claws.
One creature grappled by the Giant Crab must succeed on a DC 26 Strength saving throw or take 70 (10d10 + 10) bludgeoning damage and become restrained as the claws tighten around it. The target can escape the grapple by making a successful Strength (Athletics) check against the Crab’s grapple DC.
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Clamp Down (Recharge 5-6):
The crab makes an additional claw attack against a creature it is grappling. On a hit, the target takes an extra 3d10 bludgeoning damage as the crab crushes them further. -
Tidal Leap (Requires Water):
The crab propels itself up to 60 feet in any direction, ignoring difficult terrain in water. If it lands within 10 feet of a creature, the creature must succeed on a DC 23 Dexterity saving throw or be knocked prone. -
Shell Fortress:
The crab hunkers down, raising its AC by 2 until the start of its next turn. During this time, it heals 50% of its max HP and has an advantage on Strength and Constitution saving throws but disadvantage on Dexterity saving throws.(it can only use it 3 times per encounter battle) -
Summon Currents (Recharge 4-6):
The crab creates a 30-foot-radius vortex centered on itself. Each creature of its choice in the vortex must succeed on a DC 23 Strength saving throw or be pulled 15 feet closer to the crab.
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Snap Reflexes:
When a creature within 10 feet of the crab hits it with an attack, the crab can make a claw attack against that creature. -
Deflective Carapace:
When the crab is hit by a ranged attack, it can reduce the damage by 20 (2d10 + 10). If the damage is reduced to 0, the projectile is deflected harmlessly into the water or ground. -
Tidal Counterstrike:
When a creature within 30 feet of the crab misses it with a melee attack, the crab releases a surge of water. The attacker must succeed on a DC 23 Strength saving throw or be pushed back 20 feet and knocked prone. -
Crushing Grip:
When a creature escapes the crab’s grapple, the crab can immediately make another claw attack against that creature as a reaction. -
Elemental Fury (Recharge 5-6):
When the crab takes fire, cold, or lightning damage, it releases a burst of elemental energy. All creatures within 30 feet of it must succeed on a DC 23 Dexterity saving throw or take 4d12 damage of the triggering type.
Surging Tide (2 Actions):
The crab summons a surge of water in a 60-foot cone. Each creature in the cone must succeed on a DC 23 Strength saving throw or be pushed 30 feet away from the crab and knocked prone. Creatures in water automatically fail this saving throw unless they have a swimming speed.
Call the Deep (3 Actions):
The crab releases a powerful bellow that resonates through the ocean. Roll a d6:
- On a roll of 1-4, 1d4+1 giant crabs or 2d6 swarms of crabs appear in unoccupied spaces within 60 feet of the giant crab.
- On a roll of 5-6, 1 giant shark or 1d4 water elementals appear instead. These creatures act on initiative count 20 (losing initiative ties) and obey the crab's commands.
- Abyssal Surge (1 Action):
The crab causes the ocean floor or water around it to surge violently in a 60-foot radius. Each creature in the area must succeed on a DC 25 Strength saving throw or take 36 (8d8) bludgeoning damage and be pushed 30 feet in a direction of the crab's choice. On a successful save, creatures take half damage and are not pushed. The surge also extinguishes flames and scatters loose objects.
- Crushing Embrace (2 Actions):
The crab uses its claws to crush a grappled creature with terrifying force. The creature must make a DC 25 Constitution saving throw or take 60 (12d10) bludgeoning damage and be restrained until the end of the crab's next turn. On a successful save, the creature takes half damage and isn’t restrained.
- Ocean’s Wrath (2 Actions):
The crab channels the full force of the ocean, releasing a devastating 100-foot-radius explosion of water and force. Each creature of the crab's choice in the area must make a DC 25 Dexterity saving throw, taking 72 (16d8) force damage on a failed save, or half as much on a successful one. This ability causes massive waves and flooding, potentially reshaping the terrain in the lair.
- Tectonic Shift (3 Actions):
The crab slams its claws into the ground or seabed, causing a localized earthquake in a 120-foot radius. Each creature on the ground in the area must succeed on a DC 25 Dexterity saving throw or fall prone and take 88 (16d10) bludgeoning damage. Structures and terrain in the area may collapse or become unstable at the DM’s discretion. Water within the area churns violently, making it difficult terrain for the next minute.
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Summon the Abyssal Legion (3 Actions):
The crab calls forth its mightiest allies from the depths. It summons one of the following:- 1 kraken or
- 2 storm giants loyal to the ocean’s will or
- 4 water elementals and 6 giant sharks.
These creatures appear in unoccupied spaces within 120 feet of the crab, act on initiative count 20 (losing ties), and remain for 1 hour or until they drop to 0 hit points.
Description
Size and Appearance:
The giant crab is a truly titanic entity, dwarfing ships and towers with its massive, chitinous form. Its carapace glistens with an iridescent sheen, resembling a jagged island of coral and stone. Jagged barnacles and seaweed cling to its armored body, and its claws, each the size of a small fortress, gleam with razor-sharp edges capable of cleaving through steel like driftwood. Its eyes are luminous orbs, glowing faintly with an otherworldly light, set atop long, sinuous stalks that swivel with an eerie intelligence.
Personality and Behavior:
This colossal crab is a primal force of nature, ancient and almost inscrutable. It embodies the crushing power of the ocean depths and the relentless cycle of tides. While not inherently malicious, it is utterly indifferent to the concerns of mortals. It serves as both a protector of the ocean's deepest secrets and an unstoppable destroyer when provoked. Some cultures revere it as a god, while others fear it as a herald of destruction.
The crab is territorial and fiercely defends its domain. Intrusions are met with overwhelming force, but it may retreat if the battle threatens to damage the balance of its environment. It is cunning, using its environment and lair to outmaneuver enemies rather than relying solely on brute strength.
Abilities and Combat Style:
The giant crab fights with both raw physical might and an almost supernatural connection to the ocean. It uses its immense claws to crush ships and batter foes while manipulating tides and currents to control the battlefield. It favors grappling and isolating enemies, pulling them close where it can finish them off with devastating force.
Despite its size, the crab moves with surprising swiftness in water, able to unleash sudden bursts of speed to catch fleeing enemies or reposition. It often uses its environment to its advantage, luring enemies into underwater hazards or summoning tidal waves to sweep them into traps.
Lair and Lair Actions
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Tidal Surge:
A massive wave sweeps through the lair in a 120-foot radius centered on the giant crab. Each creature of the crab’s choice must make a DC 23 Strength saving throw. On a failed save, a creature takes 26 (4d12) bludgeoning damage and is knocked prone. On a success, the creature takes half damage and isn’t knocked prone. Structures and objects in the area may be damaged at the DM's discretion. -
Riptide Currents:
The water within the lair churns with powerful currents. Each creature in water within 120 feet of the crab must succeed on a DC 23 Strength saving throw or be pulled 30 feet closer to the giant crab. Any creature that starts its turn within 30 feet of the crab while in water is restrained unless it uses an action to succeed on another DC 23 Strength (Athletics) check to escape. -
Erupting Coral:
The ground (or seabed) within the lair erupts with razor-sharp coral in a 60-foot radius centered on a point the crab can see within 120 feet. The area becomes difficult terrain. Any creature moving through the area takes 14 (4d6) piercing damage for every 10 feet it moves. The coral sinks back into the ground after 1 minute. -
Cloud of Choking Silt:
A dense cloud of silt fills a 60-foot radius centered on the giant crab, heavily obscuring the area for all creatures except the crab. Creatures that breathe must make a DC 23 Constitution saving throw at the start of their turn or be unable to breathe until they leave the cloud. This effect lasts until the start of the crab’s next turn. -
Ocean’s Fury:
The lair trembles with the power of the ocean. All creatures standing on the ground within 120 feet of the crab must succeed on a DC 23 Dexterity saving throw or be knocked prone as the ground shifts and water erupts in violent sprays. The terrain becomes unstable and counts as difficult terrain until initiative count 20 on the next round. -
Summon Lesser Crustaceans:
The crab summons 1d4 + 2 giant crabs or 2d6 swarms of crabs (or similar aquatic creatures) to aid it. These creatures appear in unoccupied spaces within 60 feet of the crab, act on initiative count 20, and disappear after 1 minute or when reduced to 0 hit points.
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Posted Jul 7, 2025Well thought-out and written. Great job!