The dragon has resistance to damage that isn't radiant, force, or physic while in dim light or darkness. However if is hit by radiant damage it loses this resistance for two rounds

It can take the hide action as a bonus action while in dim light or darkness. However this ability does not function if it has been hit by radiant damage in the last two rounds. A player can take a DC 15 perception check to spot the dragon. If a player spots the dragon the DC is lowered to 10, and are made with advantage until the dragon uses hide again.

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

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit:  (2d10 + 5) piercing damage plus  (1d10) necrotic damage damage.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage.

Shadow breath (Recharge 5–6). The dragon exhales lightning in an 60-foot line that is 5 feet wide. Each creature in that line must make a DC 16 Dexterity saving throw, taking  (10d10) necrotic damage on a failed save, or half as much damage on a successful one.