Lightning-Spewing Glutton

Habitat: Underdark; Treasure: Any

Twelve-legged, reptilian predators, behirs endlessly hunt for their next meal. Their short legs propel them quickly across floors and walls. Any prey that behirs can’t chase down, they blast with breaths of powerful lightning.

Legends claim the first behirs were magically created by storm giants during an ancient, multiversal conflict between giants and dragons. The giants used their mastery of weather to alter the essence of blue dragons. The results were the first behirs, which served as hunters with a particular taste for dragon eggs.

Behirs live in sprawling cave systems and elaborate ruins where they can make the most of their exceptional mobility. They are mindful of areas where dragons dwell, as most dragons view behirs as dangerous abominations and attack them on sight. Nevertheless, behirs occasionally hunt for dragon lairs in the hope of finding and devouring unhatched dragon eggs.

You wouldn’t believe all the great stuff I’ve swallowed! Now just climb on in here, and you can keep whatever you find.
—Lludd, behir

Actions

Multiattack. The behir makes one Bite attack and uses Constrict.

Bite. Melee Attack Roll: +10, reach 10 ft. Hit: 19 (2d12 + 6) Piercing damage plus 11 (2d10) Lightning damage.

Constrict. Strength Saving Throw: DC 18, one Large or smaller creature the behir can see within 5 feet. Failure: 28 (5d8 + 6) Bludgeoning damage. The target has the Grappled condition (escape DC 16), and it has the Restrained condition until the grapple ends.

Lightning Breath (Recharge 5–6). Dexterity Saving Throw: DC 16, each creature in a 90-foot-long, 5-foot-wide Line. Failure: 66 (12d10) Lightning damage. Success: Half damage.

Bonus Actions

Swallow. Dexterity Saving Throw: DC 18, one Large or smaller creature Grappled by the behir (the behir can have only one creature swallowed at a time). Failure: The behir swallows the target, which is no longer Grappled. While swallowed, a creature has the Blinded and Restrained conditions, has Total Cover against attacks and other effects outside the behir, and takes 21 (6d6) Acid damage at the start of each of the behir’s turns.
    If the behir takes 30 damage or more on a single turn from the swallowed creature, the behir must succeed on a DC 14 Constitution saving throw at the end of that turn or regurgitate the creature, which falls in a space within 10 feet of the behir and has the Prone condition. If the behir dies, a swallowed creature is no longer Restrained and can escape from the corpse by using 15 feet of movement, exiting Prone.