Beast Master

Trampling Charge. If the triceratops moves at least 20 feet 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.

Awakened Mind. you have the ability to touch the minds of other creatures. You can telepathically speak to any creature you can see within 30 feet of you. You don’t need to share a language with the creature for it to understand your telepathic utterances, but the creature must be able to understand at least one language.

Spellcasting. Your awakened mind has unlocked psychic abilities with you. you have the ability to cast "dominate monster" once per day. (spell save DC 13, +5 to hit with spell attacks). Once u successfully dominate a monster whose cr is less than yours, they will become subservient forever. 

cantrips: mind sliver

1st level spells(3 slots): charm person 

4th level spells(2 slots): charm monster

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.