Actions

Multiattack. The cairnwight makes two Slam attacks or two Rock attacks, and it uses its Petrifying Touch if available.
  Slam. Melee Weapon Attack: +10 to hit, reach 2 sq., one target. Hit: 22 ( 3d10+6 ) bludgeoning damage.
  Rock. Ranged Weapon Attack: +10 to hit, 12/48 sq., one target. Hit: 19 ( 3d8+6 ) bludgeoning damage, and the target must succeed on a DC 17 Strength saving throw or have the prone condition.
  Petrifying Touch (Recharge 1d6>=5 ). The cairnwight touches one creature it can see within 2 square of itself. The target must succeed on a DC 17 Constitution saving throw or take 26 ( 4d12 ) force damage and have the restrained condition as it begins to turn to stone. The affected target must repeat the saving throw at the end of its next turn. On a successful save, the effect ends on the target. On a failed save, the target has the petrified condition instead of the restrained condition.