Adult Onyx Cloud Dragon

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 30 or less, the attack continues as normal. On a 31 or higher, the attack fails to effect the dragon. On a 80-100, the attack is redirected at the target.

Night Hunter. While in dim light or darkness, attacks against the dragon have disadvantage. In addition, any hit you score against a creature that is surprised is a critical hit, including your breath weapon.

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

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 7) piercing damage plus 4 (1d8) necrotic damage.

Tail. Melee Weapon Attack: +12 to hit, reach 5ft, one target. Hit. 1d12+7 bludgeoning damage.

Cloud Breath (Recharge 5-6). The dragon exhales black clouds in a 60­-foot cone. Each creature in that line must make a DC 18 Dexterity saving throw, taking 49 (12d8) necrotic damage on a failed save, or half as much damage on a successful one. Creatures who take damage from this breath do half damage with strength based attacks, until the end of your next turn.

Bolster (3/day). The dragon gains 20 temporary hit points.