Multiattack

The black knight commander makes one Lance attack and two Mace attacks. If the commander is mounted, its mount can then make one Hooves attack. If both Mace attacks hit one creature, the target takes an extra 7 (2d6) bludgeoning damage.

Lance

Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 10 (1d12 + 4) piercing damage.

Mace

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) bludgeoning damage.

Frightful Charge (Recharges after a Short or Long Rest)

While mounted, the black knight commander lets loose a terrifying cry. It then moves up to 30 feet in a straight line and can move through the space of any Large or smaller creature. This movement doesn't provoke opportunity attacks. The first time it enters a creature's space during this move, that creature must make a DC 15 Dexterity saving throw. On a failure, a creature takes 28 (8d6) bludgeoning damage and is frightened for 1 minute. On a success, a creature takes half the damage and isn't frightened. A frightened creature can make a DC 15 Wisdom saving throw at the end of each of its turns, ending the effect on itself on a success.