Multiattack

The dragon can use its Oil Spray. It then makes five attacks: three with its bite and two with its fists.

Bite

Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 18 (2d10 + 7) piercing damage plus 3 (1d6) fire damage.

Fist

Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 7) bludgeoning damage.

Fire Breath (Recharge 6)

The dragon exhales fire in three separate 60-foot cones. Each creature in one of these cones must make a DC 19 Dexterity saving throw, taking 45 (13d6) fire damage on a failed save, or half as much damage on a successful one. A creature in overlapping cones has disadvantage on the saving throw, but it takes damage from only one breath.

Oil Spray

The dragon sprays oil in a 30-foot-cone. Each creature in the area must succeed on a DC 19 Dexterity saving throw or become vulnerable to fire damage until the end of the dragon's next turn.

Tail Sweep

The dragon swings its bladed tail. Each creature within 15 feet of the dragon must make a DC 19 Dexterity saving throw. On a failure, a creature takes 16 (2d8 + 7) slashing damage and is knocked prone. On a success, a creature takes half the damage but isn't knocked prone.