Iceworm

Amphibious. Can breathe air and water.

Cold Physiology. Can't abide constant warmth. Each hr it spends in an area with temperature above 40 degrees Fahrenheit worm must make DC 15 Con save or suffer one level of exhaustion that can't be removed until it finishes a long rest in area with temperature below 40 degrees.

Heat Sensitivity. Has disadvantage on attack rolls when within 5 ft. of a strong source of heat that isn't a warm-blooded creature's natural warmth such as a torch or campfire. In addition the iceworm can pinpoint the location of warm-blooded creatures within 90' of it and can sense the general direction of such creatures within 1 mile of it.

Slippery. Has advantage on saves and ability checks made to escape a grapple.

Icy Bite. Melee Weapon Attack: +5 to hit, 5 ft., one creature,. 5 (1d4+3) piercing damage + 7 (2d6) cold.

Icy Spit. Ranged Weapon Attack: +5 to hit 20/60' one creature. 10 (2d6+3) cold and target is coated in freezing viscous slime. While coated creature's speed reduced by 10 ft. and has disadvantage on 1st attack roll it makes on each of its turns. Creature including target can use action to clean off the slime ending effect.