Cave Dragon Wyrmling

Tunneler. The cave dragon can burrow through solid rock at half its burrowing speed and leaves a 5-foot wide, 5-foot high tunnel in its wake.

Innate Spellcasting. the dragon's innate spellcasting ability is Charisma. It can innately cast the following spell, requiring no material components: 3/day: darkness

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage plus 3 (1d6) poison damage.

Poison Breath (Recharge 5-6). The dragon exhales a cone of black poison gas in a 15-foot cone. Each creature in that area must make a DC 13 Constitution saving throw, taking 14 (4d6) poison damage on a failed save and the target is poisoned if it is a creature. The poisoned condition lasts until the target takes a long or short rest or removes the condition with lesser restoration. If the save is successful, the target takes half the damage and does not become poisoned.