Bluecrest Manta Ray

Luminescence. The manta ray's body glows with faint blue light, which can be seen up to 60 feet away.

Powerful Bite. The manta ray's bite attack deals an extra 3 (1d6) damage

Multiattack. The manta ray makes two attacks: one with its bite and one with its tail slap.

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 3 (1d6) extra damage.

Tail Slap. Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 20 (3d8 + 6) bludgeoning damage.

Luminescent Aura (2/day). The manta ray emits a bright burst of blue light in a 15-foot radius around itself. Creatures within the radius must succeed on a DC 16 Constitution saving throw or be blinded 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

Luminescent Blitz (2/day). As an action, the manta ray charges towards a target within 60 feet of it, leaving a trail of luminescent energy behind it. The target must make a DC 14 Dexterity saving throw, taking 21 (6d6) lightning damage on a failed save, or half as much damage on a successful one. The manta ray can then use its bonus action to move up to half its speed.