Ancient Calstil

False Appearance. When the calstil remains motionless, it is mistaken for a hill.

Multiattack. The calstil can use its Deafening Moo. It then makes two Stomp attacks.

Stomp. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) bludgeoning damage. On hit, each creature within 20 ft. of the target, including the target, must make a DC 18 Dexterity saving throw. On a fail, the participant of the check falls prone and takes 7 (1d12 ) damage. On success, the participant falls prone but takes no damage.

Deafening Moo. The calstil lets out a thunderous bellow. Each creature within 360 ft. of the calstil takes 13 (2d12) thunder damage and is Deafened until the end of the calstil's next turn.