Multiattack

The caustic charger makes two Ram attacks. It can replace one Ram attack with a Tentacles attack.

Ram

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 22 (4d8 + 4) bludgeoning damage, and if the target is a Large or smaller creature, it must succeed on a DC 15 Strength saving throw or be knocked prone. If the charger moved at least 10 feet straight toward the target immediately before the hit, the target has disadvantage on the saving throw.

Tentacles

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) bludgeoning damage plus 14 (4d6) acid damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw or be paralyzed for 1 minute. The paralyzed creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If the caustic charger attacks a target that is not in the charger's space, the target takes half the acid damage and has advantage on the saving throw.