Crag 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 22 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 14 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: +17 to hit, reach 15 ft., one target. Hit: 32 (4d8 + 10) piercing damage. If the target is a creature, it is grappled (escape DC 19). Until this grapple ends, the target is restrained, and the linnwyrm can’t bite another target.

Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 24 (3d8 + 10) slashing damage.

Tail. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 24 (3d8 + 10) bludgeoning damage.

Swallow. The linnwyrm makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite’s damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the linnwyrm, and it takes 56 (16d6) acid damage at the start of each of the linnwyrm’s turns.

If the linnwyrm takes 60 damage or more on a single turn from a creature inside it, the linnwyrm must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the linnwyrm. If the linnwyrm dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 30 feet of movement, exiting prone.