Light Absorption. If the light devourer spends any part of its turn in an area of bright light or is subjected to radiant damage, it radiates dim light in a 10-foot radius for 1 hour.
Water Breathing. The light devourer can breathe only underwater.
Multiattack. The light devourer makes two Bite attacks.
Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit:21 (5d6 + 4) piercing damage, or radiant damage if the light devourer is radiating light (see Light Absorption).
Radiant Discharge. If the light devourer is radiating light (see Light Absorption), it releases the light stored in its body in a 20-foot-radius sphere centered on itself, then ceases to radiate light. Each creature in the sphere must make a DC 15 Constitution saving throw, taking 24 (7d6) radiant damage on a failed saving throw, or half as much damage on a successful one.
The light devourer gets its name from its ability to absorb bright light, whether natural or magical, in its immediate environment. After doing so, the creature begins to glow, the spines lining its back and the numerous needle-like teeth in its maw burning brightly as it converts that stolen light into searing energy, which rips into its prey.