uncommon ce gargantuan amphibious dragon 

Perception +27; darkvision, scent (imprecise) 60 feet, true seeing

Languages Aklo, Draconic, Sylvan

Skills Acrobatics +28, Athletics +31, Stealth +28

Str +8 Dex +5 Con +7 Int -3 Wis +6 Cha +7

AC  38; Fort +29, Ref +25, Will +22

HP 295, regeneration 10 (deactivated; Immunities fire, curse, paralyzed, sleep; Weaknesses cold iron 10

Curse of Drowning (curse, primal, water) When a creature slays a shoal linnorm, it must succeed at a DC 38 Will save or become cursed. As long as the curse of drowning persists, the character must spend 3 actions when drinking any liquid. Attempting to drink liquid faster causes the victim to begin drowning, immediately running out of air and falling unconscious.

Attack of Opportunity [R] Tail only.

Speed 35 feet, fly 100 feet, swim 100 feet; freedom of movement

Melee [>] jaws +31 (magical, reach 20 feet), Damage 3d12+16 piercing plus shoal linnorm venom

Melee [>] claw +31 (agile, magical, reach 15 feet), Damage 3d8+16 slashing

Melee [>] tail +31 (magical, reach 25 feet), Damage 4d6+16 bludgeoning plus Improved Grab

Primal Innate Spells DC 36; Constant (7th) freedom of movement; (6th) true seeing

Breath Weapon [>>] (evocation, fire, primal, water) The shoal linnorm exhales scalding steam that deals 12d8 fire damage in a 60-foot cone (DC 36 basic Reflex save). The steam lingers until the end of the linnorm's next turn; anyone who enters the area or begins their turn in the area takes 6d8 fire damage (DC 36 Reflex save negates) During this time, the steam is so thick that it impedes movement as well as sight, turning the area into difficult terrain. All creatures in the steam become concealed, and all creatures outside the steam become concealed to creatures within it. The shoal linnorm can't use Breath Weapon again for 1d4 rounds.

Shoal Linnorm Venom (fire, poison) Saving Throw DC 36 Fortitude; Maximum Duration 10 rounds; Stage 1 4d6 fire damage and enfeebled 1 (1 round); Stage 2 6d6 fire damage and enfeebled 2 (1 round)

Bestiary 2, page 164.