Ankheg

The ankheg spits acid in a line that is 30 feet long and 5 feet wide, provided that it has no creature grappled. Each creature in that line must make a DC 13 Dexterity saving throw, taking 10 (3d6) acid damage on a failed save, or half as much damage on a successful one.

Dexterity Saving Throw: DC 12, each creature in a 30-foot-long, 5-foot-wide Line. Failure: 14 (4d6) Acid damage. Success: Half damage.

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) slashing damage plus 3 (1d6) acid damage. If the target is a Large or smaller creature, it is grappled (escape DC 13). Until this grapple ends, the ankheg can bite only the grappled creature and has advantage on attack rolls to do so.

Melee Attack Roll: +5 (with Advantage if the target is Grappled by the ankheg), reach 5 ft. Hit: 10 (2d6 + 3) Slashing damage plus 3 (1d6) Acid damage. If the target is a Large or smaller creature, it has the Grappled condition (escape DC 13).