High Fliers. The dragon can breathe in any area that has an amount of air, no matter how thin. It can hold it's breath for up to ten minutes at a time.

Onyx Scales. If the dragon would be subjected to an attack or effect that deals necrotic damage, roll 1d100. On a 50 or less, the attack continues as normal. On a 51 or higher, the attack fails to effect the dragon. On a 90-100, the attack is redirected at the target.

Actions

 Multiattack. The dragon makes three attacks: one with its bite and two with its tail.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d10 + 5) piercing damage plus 2 (1d8) necrotic damage.

Tail. Melee Weapon Attack: +7 to hit, reach 5ft, one target. Hit. 1d12+4 bludgeoning damage.

Cloud Breath. The dragon exhales black clouds in a 30­-foot line that is 5 feet wide. Each creature in that line must make a DC 14 Dexterity saving throw, taking 49 (11d8) necrotic damage on a failed save, or half as much damage on a successful one.

Bonus Actions

Bolster (1/day). The dragon gains 10 temporary hit points