Karkinos

Karkinos is the giant crab that entered a heroic struggle to aid the Hydra, attacking from below while the greater monster held attention. Though crushed in the tale, its loyalty and timing earned a place among the stars. Karkinos is a massive armored ambusher whose danger comes from entering a struggle already underway and choosing the worst possible moment.

Hero's Ankle: bludgeoning, melee 10 ft, +8 to hit, 4d8+6. A target engaged with another enemy makes a Quick save or falls down and becomes held. A successful save prevents both effects but does not undo the attack damage. Star-Shell Rush: Karkinos moves up to 40 ft in a straight line. Creatures crossed make Quick saves or take 4d10 bludgeoning damage and move 15 ft; no creature can be struck twice by the rush. A successful save avoids the damage and movement.

Crushed from Above: bludgeoning damage from a Huge creature or falling object ignores DR. Karkinos releases its target if the creature it came to aid is defeated or retreats.