Purple Worm

Gargantuan monstrosity, unaligned

Armor Class 18 (natural armour)

Hit Points 247 ( 15d20+90 )

Speed 50ft Burrow: 50ft

STR

28 +9

DEX

7 -2

CON

22 +6

INT

1 -5

WIS

8 -1

CHA

4 -3

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

Languages -

Challenge 15

Tunneler. The worm can burrow through solid rock at half its burrow speed and leaves a 10-foot-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: +9 to hit, reach 10 ft., 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 10 feet of the worm. If the worm dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 20 feet of movement, exiting prone.
Tail Stinger. Melee Weapon Attack: +9 to hit, reach 10 ft., 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.