Multiattack

The crimson drake makes one bite attack and one stinger attack.

Bite

Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage plus 4 (1d8) fire damage.

Stinger

Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) piercing damage, and the target must succeed on a DC 13 Constitution saving throw or become poisoned for 1 hour. If the saving throw fails by 5 or more, the target takes 2 (1d4) poison damage at the start of each of its turns for 3 rounds. The target may repeat the saving throw at the end of its turn to end the effect early.

Breath Weapon (Recharge 6)

The drake exhales fire in a 15-ft. cone. Each target in that cone takes 18 (4d8) fire damage, or half damage with a successful DC 12 Dexterity saving throw.