Multiattack. The Crystal Bat makes 3 attacks one Bite, one Wing, and Summons one Crystal Pillar.

Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 14 (2d10 + 3) piercing damage plus 4 (1d8) radiant damage and inflicts Crystal Parasites.

Crystal Wing Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashing damage and inflicts crystal parasites (see below).

Scintillating Breath (Recharge 5–6). The Crystal Bat exhales a burst of brilliant radiance in a 30-foot cone. Each creature in that area must make a DC 15 Constitution saving throw, taking 27 (6d8) radiant damage on a failed save and inflicts Crystal Parasites, or half as much damage on a successful one. The Crystal Bat then gains 10 temporary hit points by absorbing a portion of the radiant energy.

Summon Crystal Pillar. The Crystal Bat summons a 10-foot pillar of crystal at a point it can see within 60ft. The pillar has 20 HP and a Hardness of 15. Each creature in that area must make a DC 15 Dexterity saving throw, taking 24 (3d10) bludgeoning damage on a failed save, or half as much damage on a successful one. The Crystal Bat then gains 10 temporary hit points by absorbing a portion of the Sonic energy. In addition when within 5 feet of a Crystal Pillar the Crystal Bat can as a move action lunge at the pillar and use it as a spring board to glide or fly to a spot it can see costing half the normal movement speed

Crystal Parasites (DC 13 Arcana for knowledge). While subjected to Crystal Parasites a creature suffers from crystals that seem to grow rapidly along its epidermis crystalizing the flesh as it grows, granting the afflicted creature vulnerability to Thunder Damage. This can be cured by a lesser restoration or equivalent spell. Additional methods at DM's discretion.

The Crystal Bat can take 3 legendary actions, using the options below. It can take only one legendary action at a time and only at the end of another creature’s turn. The Crystal Bat regains spent legendary actions at the start of its turn.

Crystal Pillar Attunement (1 action). Over time the pillars attune to the vibrations of the Prime Material Plane and then release this stored energy in a sonic attack Each creature in within 10ft of a Crystal Pillar must make a DC 15 Constitution saving throw, taking 24 (3d10) thunder damage on a failed save, or half as much damage on a successful one. The Crystal Pillar takes the full amount of Damage

Summon Crystal Pillar (1 action) The Crystal Bat summons a 10-foot pillar of crystal at a point it can see within 60ft. The pillar has 20 HP and a Hardness of 15. Each creature in that area must make a DC 15 Dexterity saving throw, taking 24 (3d10) bludgeoning damage on a failed save, or half as much damage on a successful one. The Crystal Bat then gains 10 temporary hit points by absorbing a portion of the Sonic energy.

Cataclysm (3 actions) The Crystal Bat sonic screech and triggers up to 4 crystal pillars it can see within 120ft as if using Crystal Pillar Attunement.