Immutable Form. The Rock is immune to any spell or effect that would alter its form.

Magic Resistance. The Rock has advantages on saving throws against spells and other magical effects.

Magic Weapons. The Rock's weapon attacks are magical.

Multiattack. The Rock makes two attacks.

Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) bludgeoning damage. 

The Rock Bottom. On a successful grapple, The Rock wraps one arm around the target's upper body. He mugs to everyone visible, and then lifts the target high into the air and slams them into the ground dealing 4d8+6 bludgeoning damage. The target must succeed on a DC 17 Dexterity saving throw to take half damage and remain standing, otherwise they are knocked prone and take full damage.

The Pebbles Elbow. As a bonus action, The Rock strikes a self-assured pose over a prone target. With a high degree of flair, he bounces off objects around the battlefield, leaps high into the air, and comes down from the sky to smash a rocky elbow into the target's ribs, dealing 6d8+6 bludgeoning damage. If the target succeeds a DC 15 Constitution saving throw the muster up enough internal fortitude to move at the exact right moment and The Rock deals the damage to himself.