Purple Worm

Gargantuan monstrosity, unaligned

Armor Class 18 (natural armor)

Hit Points 247 (15d20+90)

Speed 50ft., burrow 30ft.

Saving Throws Con +11, Wis +4

Senses blindsight 30ft., tremorsense 60ft., passive Perception 9

Languages -

Challenge 15 (13,000 XP)

Traits

Tunneler

The worm can burrow through solid rock at half its burrow speed and leaves a 10ft diameter tunnel in its wake.

Actions

Multiattack

The worm makes two attacks: one with its bite and one with its stinger.

Bite

Melee Weapon Attack: +14 to hit, reach 10ft., one target.
Hit: 22 (3d8+9) piercing damage. If the target is a Large or smaller creature, it must succeed on a DC 19 Dexterity saving throw or be swallowed by the worm. A swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the worm, and it takes 21 (6d6) acid damage at the start of each of the worm's turns.

If the worm takes 30 damage or more on a single turn from a creature inside it, the worm must succeed on a DC 21 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10ft of the worm. If the worm dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 20ft of movement, exiting prone.

Tail Stinger

Melee Weapon Attack: +14 to hit, reach 10ft., one creature.
Hit: 19 (3d6+9) piercing damage, and the target must make a DC 19 Constitution saving throw, taking 42 (12d6) poison damage on a failed save, or half as much damage on a successful one.