Trampling Charge. If the triceratops moves at least 20 ft. straight toward a creature and then hits it with a gore attack on the same turn, that target must succeed on a DC 13 Strength saving throw or be knocked prone. If the target is prone, the triceratops can make one stomp attack against it as a bonus action.
Gore. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 24 (4d8 + 6) piercing damage.
Stomp. Melee Weapon Attack: +9 to hit, reach 5 ft., one prone creature. Hit: 22 (3d10 + 6) bludgeoning damage.