Black Tortoise Ninja

Charger. If the Black Tortoise Ninja moves at least 10 feet straight toward a target and then hits it with a slam attack on the same turn, the target takes an extra 6 (2d6) bludgeoning damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be pushed up to 10 feet away and knocked prone. 

Slam. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 6 (1d6 + 3) bludgeoning damage.

Brutal Iron Greatclub. Melee Weapon Attack: +5 to hit, reach 5ft., one target. Hit: 11 (2d8 + 3) bludgeoning damage. If the target is a creature, it must succeed on a DC 13 Strength saving throw or be pushed to 10 feet and knocked prone.

Meteor Drop (1/Day). The Black Tortoise Ninja leaps forward 30 feet. Each creature within 10 feet of where the Black Tortoise Ninja lands must succeed on a DC 13 Strength or Dexterity saving throw or be knocked prone. If a creature is occupying the space where the Black Tortoise Ninja would land it makes a Slam attack against them. If the creature is hit it takes an addition 1d6 bludgeoning damage and is knocked prone in the Black Tortoise Ninja's space and restrained. It must succeed a DC 15 Strength check at the end of each of it's turns to end the effect while the Black Tortoise Ninja occupies the space. On a success the creature moves to an empty adjacent space and stands.

Reactive Stomp (1/Day). If the Black Tortoise Ninja is targeted with a ranged attack it can use it's reaction to create a 5 foot tall, 5 foot wide wall of stone directly in front of it granting it total cover.