Purple Worm
Gargantuan Monstrosity, unaligned
13,000 XP
Special Abilities
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: +14 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: +14 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.
Quick Reference
Running This Encounter
The Purple Worm is a devastating apex predator best used as a catastrophic encounter that tests party resources and tactical ingenuity. Position it in an underground cavern or tunnel system where its size (60 feet long) can be fully utilized. Use the terrain to your advantage—narrow passages force the party into vulnerable positions while open areas allow the worm to demonstrate its terrifying mobility. Consider having it emerge mid-encounter or use it as a climactic boss fight where the party must either defeat it or escape.
Combat Tactics
The Purple Worm attacks with its bite (dealing massive piercing damage) and stinger tail (delivering poison damage) while using its burrowing speed to reposition unpredictably. It prioritizes full attacks on frontline combatants and uses legendary actions to maintain pressure. When bloodied, it may retreat underground and re-emerge elsewhere, forcing the party to adapt their positioning.
Environment & Setting
Underground caverns, deep dungeon networks, or the Underdark provide ideal settings where the worm's burrowing ability and size create environmental hazards. Cavern pillars, chasms, and unstable terrain can add complexity to the encounter.