Psychic Maelstrom. Any creature that starts its turn within 15 feet of the shark must succeed on a DC 17 Wisdom saving throw or take 11 (2d10) psychic damage.
Regeneration. The shark regains 10 hit points at the start of its turn. If the shark takes radiant damage or suffers a critical hit, this trait doesn't function at the start of its next turn. The shark dies only if it starts its turn with 0 hit points and doesn't regenerate.
Water Breathing. The shark can breathe only underwater.
Bite. Melee Weapon Attack: +10 to hit (with advantage if the target is a creature missing any hit points), reach 5 ft., one target. Hit:22 (3d10 + 6) piercing damage, and if the target is a creature, it must succeed on a DC 17 Charisma saving throw or gain 1 level of exhaustion.
In addition to its vicious bite, this giant shark projects a psychic aura that causes painful mental distress in other creatures nearby. The crystals that corrupt the shark's body enable it to regenerate, and only radiant energy or particularly devastating attacks can overcome this unnatural defense.