Traits
Amphibious
The wellwyrm can breathe air and water.
Hunting Terror
If the wellwyrm hears a creature play a horn or similar Musical Instrument, it has the Frightened condition until the end of its next turn.
Actions
Multiattack
The wellwyrm makes one Bite attack and uses Constrict.
Bite
Melee Attack Roll: +8, reach 10 ft. Hit: 15 (2d10 + 4) Piercing damage plus 21 (6d6) Poison damage.
Constrict
Strength Saving Throw: DC 16, one Medium or smaller creature the wellwyrm can see within 5 feet. Failure: 13 (2d8 + 4) Bludgeoning damage. The target has the Grappled condition (escape DC 14), and it has the Restrained condition until the grapple ends. The wellwyrm needn't spend extra movement to move during this grapple.