Void creature. The leviathan doesnt need to breath. Anything within 6 km of the leviathan can only hear the leviathan, and is considered deaf to all other sounds.
Legendary Resistance (3/Day). If the leviathan fails a saving throw, it can choose to succeed instead.
Multiattack. The leviathan can use its Frightful Presence. It then makes three attacks: two with its bite and one with its tail.
Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 21 (3d10 + 6) piercing damage plus 5 (1d10) acid damage.
Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 16 (2d10 + 6) bludgeoning damage.
Frightful Presence. Each creature of the leviathans choice that is within 120 feet of the dragon and aware of it must succeed on a DC 16 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the leviathans Frightful Presence for the next 24 hours.
Void thunder (Recharge 5–6). The leviathan Summons purpleish lighting Within 60 ft of it. The target creature must make a DC 20 Dexterity saving throw, taking 54 (12d8) lighting damage on a failed save, or half as much damage on a successful one.
The leviathan can take 3 legendary actions, 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 leviathan regains spent legendary actions at the start of its turn.
Detect. The leviathan makes a Wisdom (Perception) check.
Tail Attack. The leviathan makes a tail attack.
Bite attack. The leviathan makes a bite attack
Description
The leviathan is a large serpentine creature, covered in some sort of exoskeleton carapace.
It is said to be summoned by the gods to kill whoever they ask for.