Adult Linnwyrm

Keen Smell. The linnwyrm has advantage on Wisdom (Perception) checks that rely on smell.

Amphibious. The linnwyrm can breathe air and water.

Pounce. If the linnwyrm moves at least 20 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 19 Strength saving throw or be knocked prone. If the target is prone, the linnwyrm can make one bite attack against it as a bonus action.

Regeneration. The linnwyrm regains 10 hit points at the start of its turn if it still has at least 1 hit point. If the linnwyrm takes psychic or poison damage, this trait doesn't function at the start of the linnwyrm's next turn. The linnwyrm dies only if it starts its turn with 0 hit points and doesn't regenerate.

Reckless. At the start of its turn, the linnwyrm can gain advantage on all melee weapon attack rolls during that turn, but attack rolls against it have advantage until the start of its next turn.

Multiattack. The Linnwyrm makes four attacks. Two with its claws, one with its tail, and one with its bite.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 21 (3d8 + 8) piercing damage.

Claw. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +13 to hit, reach 20 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.