Sathaq Worm

The sathaq worms' presence induces pain in creatures native to the Material Plane. Any creature that starts its turn within 30 feet of the sathaq worm must make a DC 17 Fortitude saving throw. On a failed save, the creature is poisoned until the start of its next turn. If a creature's saving throw succeeds, it is immune to the sathaq worm's Agonizing Aura for the next 24 hours.

The sathaq worm can burrow through nonmagical, unworked earth and stone. While doing so, the elemental doesn't disturb the material it moves through.

Stealth +6 in sand, mud, or stone terrain

The sathaq worm deals double damage to objects and structures.

Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 24 (4d8 + 6) piercing damage.

If the target is a Large or smaller creature, it must succeed on a DC 18 Dexterity saving throw or be swallowed by the sathaq worm. A swallowed creature is blinded and restrained, has total cover against attacks and other effects outside the worm, and takes 7 (2d6) bludgeoning damage plus 7 (2d6) slashing damage plus 7 (2d6) acid damage at the start of each of the sathaq worm's turns. The sathaq worm can have only one creature swallowed at a time. If the sathaq worm takes 20 damage or more on a single turn from a creature inside it, the sathaq worm must succeed on a DC 15 Constitution saving throw at the end of that turn or regurgitate the swallowed creature, which falls prone in a space within 5 feet of the sathaq worm. If the sathaq worm dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 10 feet of movement, exiting prone.