Each creature of the whale's choice within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns with disadvantage if the whale is within line of sight ending the effect on itself on a success. If a creatures saving throw is successful or the effect ends for it the creature is immune to the whale's Frightful Presence for the next 24 hours.
Melee Weapon Attack: +19 to hit reach 20 ft. one target. Hit: 24 (4d6 + 10) bludgeoning damage. If the target is a creature it must succeed on a DC 20 Strength saving throw or be knocked prone.
Balleen of Lightning:
Melee Weapon Attack: +17 to hit reach 10 ft. all creatures within a 15ft diameter are targeted. Hit: 23 (3d8 + 10) lightning damage. If the target is a creature it is grappled/stunned (escape DC 20). Until this grapple/stun ends the target is restrained.
If the target is a Large or smaller creature grappled by the storm whale that creature is swallowed and the grapple ends. While swallowed the creature is blinded and restrained it has total cover against attacks and other effects outside the whale and it takes 42 (12d6) lightning damage at the start of each of the whale's turns. If the whale takes 50 damage or more on a single turn from a creature inside it the whale must succeed on a DC 25 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures which fall prone in a space within 10 feet of the storm whale. If the storm whale dies a swallowed creature is no longer restrained by it and can escape from the corpse using 30 feet of movement exiting prone.
Can take 3 Legendary Actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature's turn. Spent legendary actions are regained at the start of each turn.