Magic Resistance. The wurm has advantage on saving throws against spells and other magical effects.

Tunneler. The wurm can burrow through solid rock at half its burrowing speed and leaves a 2-and-a-half-foot-diameter tunnel in its wake.

Unusual Nature. The wurm doesn’t require air, food, drink, or sleep.

Multiattack. The wurm makes two mind-bending bite attacks.

Mind-Bending Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) necrotic damage, and the target must succeed on a DC 10 Intelligence saving throw or it can’t take a reaction until the end of its next turn. Moreover, on its next turn, the target must choose whether it gets a move, an action, or a bonus action; it gets only one of the three.

Ovipositor. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: The target contracts the magical parasitic disease known as death wurms. Every 24 hours the diseased character must succeed a DC 6 Constitution saving throw or lower their Constitution Score by 1 until the disease is cured.

Death wurms were originally created by powerful aberrations and can be commanded and controlled by such creatures. Certain magical properties were given to death wurms to prevent other magics from curing the disease. Death wurms can be cured but only by an aberration that is powerful enough to command the creatures to leave an infected host. A creature that dies from this disease is completely eaten from the inside out and 5 (2d4) adolescent death wurms emerge from it's corpse.