Charge - Rhinoceros

Monster Manual - 5e, D&D Basic Rules

Charge. If the rhinoceros moves at least 20 feet straight toward a target and then hits it with a gore attack on the same turn, the target takes an extra 9 ( 2d8 ) bludgeoning damage. If the target is a creature, it must succeed on a DC 15 Strength saving throw or be knocked prone.