Armor Class 17 (natural armor)
Hit Points 229 (17d10 + 136)
Speed 30 ft., fly 60 ft., swim 90 ft.
Saving Throws DEX +5, WIS +7, CHA +8
Damage Resistances acid, cold, lightning
Senses blindsight 30 ft., darkvision 120 ft., passive Perception 13
Languages Aquan
Challenge 11
Amphibious. The marid can breathe air and water.
Elemental Demise. If the marid dies, its body disintegrates into a burst of water and foam, leaving behind only equipment the marid was wearing or carrying.
Multiattack. The marid makes two trident attacks.
Trident. Melee or Ranged Weapon Attack: +10 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 13 (2d6 + 6) piercing damage, or 15 (2d8 + 6) piercing damage if used with two hands to make a melee attack.
Water Jet. The marid magically shoots water in a 60-foot line that is 5 feet wide. Each creature in that line must make a DC 16 Dexterity saving throw. On a failure, a target takes 21 (6d6) bludgeoning damage and, if it is Huge or smaller, is pushed up to 20 feet away from the marid and knocked prone. On a success, a target takes half the bludgeoning damage, but is neither pushed nor knocked prone.
Monster Manual (2014), p. 146