Homebrew
Superior Darkvision 120ft., Underwater Tremorsense 120ft., passive Perception 11
Multiattack. The Plumopod makes two bite attacks or one bite and one forcipule grapple.
Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) 2d6+4 piercing damage
Forcipule Grapple. Melee Weapon Attack +8 to hit, reach 10ft., one target. On a hit, the target must make a Dexterity Saving Throw (DC: 16) or take 4 (1d8) 1d8 piercing damage, 4 (1d8) 1d8 poison damage and become Grappled.
Gaseous Puff. (Recharge 5-6) The Plumopod releases a puff of noxious gas. All creatures within a 15ft. radius sphere must make a DC 14 Constitution Saving Throw. On a failed save, targets take 18 (4d8) poison damage. On a successful save, targets take half damage.
The Plumopod Eel, also called the Featherfoot Eel, is a type of necrotically mutated amphibious vertebrate with features that resemble Chilopods. It is thought that Plumopods mutated from temperate-freshwater dwelling Moray Eels, which were an unusual occurrence in the first instance, though it is not known if any other creatures were involved in the mutation process.
The Plumopod Eel can only be found on the Isle of Swords, which is a magically necrotised environment.