Ice Worm

Tunneler. The worm can tunnel through earth and solid rock, leaving behind a 10-foot-diameter tunnel.

Sense Heat. The worm senses warm-blooded creatures and warm objects within 60 feet.

Multiattack. The worm attacks two different targets with its bite and its tail stinger.

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 25 (3d10 + 9) piercing damage. If the target is a Large or smaller creature it makes a DC 19 Dexterity saving throw. On a failure the target is swallowed. A swallowed creature is blinded and restrained it has total cover from attacks from outside the worm and it takes 24 (7d6) acid damage at the start of each of the worms turns.

If a swallowed creature deals 35 or more damage to the worm in a single turn, or if the worm dies, the worm vomits up all swallowed creatures.

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

Fighting Retreat. When a creature makes an opportunity attack on the worm, the worm attacks with either its bite or its tail stinger.