Large Dragon, neutral evil
Armor Class 18 (natural armor)
Hit Points 152 (16d10+64)
Speed fly +80, swim +50, walk +40
Challenge 9
Saving Throws cha +7, con +8, dex +4, wis +5
Skills stealth +4, perception +9
Damage Immunities cold
Senses blindsight 30 ft. darkvision 120 ft., passive Perception 19
Languages Common, Draconic
Source: Tome of Beasts · OGL/Open
Amphibious. The dragon can breathe air and water.
Siege Monster. The dragon deals double damage to objects and structures
Multiattack. The dragon makes three attacks: one with its bite and two with its claws.
Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage plus 5 (1d10) cold damage.
Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage.
Tidal Breath (Recharge 5-6). The dragon exhales a crushing wave of frigid seawater in a 30-foot cone. Each creature in that area must make a DC 16 Dexterity saving throw. On a failure, the target takes 27 (5d10) bludgeoning damage and 27 (5d10) cold damage, and is pushed 30 feet away from the dragon and knocked prone. On a successful save the creature takes half as much damage and isn't pushed or knocked prone.