Innate Spellcasting. The dragon's innate spellcasting ability is wisdom (spell save DC 14, +6 to hit with spell attacks). It can innately cast the following spells:

2/day each: entangle, dispel magic,

As a bonus action, 2/day each: invisibility, fog cloud

Multiattack. The dragon makes three attacks: one with its bite and two with its claws, or one with its charge or spellcasting followed by one with its claws. 

Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 4) piercing damage plus 7 (2d6) poison damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Poison Breath (Recharge 5–6). The dragon exhales poisonous gas in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking 42 (12d6) poison damage on a failed save, or half as much damage on a successful one.

Charge (Recharge 5-6).  Melee Weapon Attack: +7 to hit, reach 5 ft., one target. The dragon moves up to 30 feet in one direction.  Regardless of the attacking hitting, if the target is large or smaller they must make a DC 14 strength save, being forced prone on a failed save.  Hit: 15 (3d10+4) bludgeoning damage.