Three-Winged. The twins are clumsy in flight and attacks against them have advantage whilst they're on the wing.

Two Heads are Better Than One. Each twin can take a reaction, although they can't both react to the same opportunity.

Multiattack. The twins make five attacks: two bites and three claw swipes. However, due to the difficulty of coordinating their attacks and balance, a given enemy can only be the target of one claw and bite at most; and the two bite targets must be adjacent to one another.

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

Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage.

Flame Spit (Bonus action). Zelithasphex exhales a focused jet of flame at a target up to 60 feet away. The target must make a DC 13 Dexterity saving throw, taking 14 (4d6) fire damage on a failed save, or half as much damage on a successful save. If the target is 30 feet away or further, Vesthesys can provide a supporting blast which causes the saving throw to suffer disadvantage. If she does so, however, she suffers a -1 penalty to her Fire Breath recharge roll on the following turn.

Fire Breath (Recharge 5–6). Vesthesys exhales fire in a 30-foot cone. Each creature in the area must make a DC 17 Dexterity saving throw, taking 56 (16d6) fire damage on a failed save, or half as much damage on a successful one.

Shielding Wing. The twins gain half cover against a single attack. They can't use this reaction in flight, and only one of them can use it per round.