Ancient Behemoth

Tremor Steps. The behemoth shakes the ground just by walking. Whenever it walks 5 or more feet in any direction, all other creatures within 10 feet of its path and in contact with the ground must make a DC 14 Strength saving throw to avoid being knocked Prone.

Legendary Resistance (5/Day). If the behemoth fails a saving throw, it can choose to succeed instead.

Multiattack. The behemoth can use its Bedrock Spike then make three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 22 (2d12 + 9) Piercing Damage.

Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 18 (2d8 + 9) Slashing Damage.

Bedrock Spike (Recharge 5-6). The behemoth manipulates the earth around it and causes sharp spikes of bedrock to shoot from the ground. It chooses a 15 square foot area within 120 feet of it that it can see, and sharp stones erupt from the earth in that location. All creatures inside the area must make a Dexterity saving throw against a save DC of 19, taking 6d12 Piercing Damage on a failure or half as much on a success. The stones crumble into harmless sand immediately after.

The behemoth can take up to 3 legendary actions per round, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The behemoth regains spent legendary actions at the start of its next turn.

Dash. The behemoth may take a move action.

Swipe. The behemoth may make a single Claw attack against a creature within range.

Roar. The behemoth roars loudly to intimidate its foes. All creatures within 120 feet must make a Wisdom saving throw against a save DC of 19, becoming Frightened of the behemoth for 1 hour on a failure. Frightened creatures may reattempt the saving throw at the end of each of their turns, removing the condition on a success. Creatures that succeed on the save against the fear are immune to this ability for the next 24 hours.