Auroral Megalops (5e Creature)
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Huge beast, unaligned
Amphibious. The auroral megalops can breathe air and water.
Charge. If the auroral megalops moves at least 20 feet straight toward a target and then hits it with a ram attack on the same turn, the target takes an extra 9 (2d6 + 2) bludgeoning damage. If the target is a creature, it must succeed on a DC 18 Strength saving throw or be knocked prone.
Variable Illumination. The auroral megalops can shed dim light in a 30 foot radius. As a bonus action, it can stop or start emitting light.
Multiattack. The auroral megalops makes three attacks, one ram and two claw.
Claw. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 13 (4d4 + 3) slashing damage, and the target is grappled (escape DC 16).
Ram. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 16 (3d6 + 6) bludgeoning damage.
A massive golden crab which inhabits suitably large bodies of water in the underdark. The term "auroral megalops" is the collective name given to the immature forms of several distinct species of crustacean. No matter the species, however, they grow slowly but steadily throughout their lives with no real upper limit on how long they can live or large they can grow; one individual is said to support an entire city on its back.