Adult Black Dragon Lich

Ambusher. When submerged in water, the dragon has advantage on Stealth checks. If the dragon hits a creature that can't see it with its bite, it can deal piercing damage and grapple the target simultaneously.

Innate Spellcasting. The dragons spellcasting ability is Charisma (save DC 17). It can innately cast the following spells, requiring no material components. 3/day each: animate dead, fog cloud, legend lore, pass without trace, speak with dead

Multiattack. The dragon attacks once with its bite and twice with its claws. In place of its bite attack it can use Acid Spit.

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 22 (3d10 + 6) piercing damage plus 4 (1d8) acid damage. Instead of dealing piercing damage the dragon can grapple the target (escape DC 20) and a Large or smaller creature grappled in this way is restrained. While grappling a creature the dragon can't bite or use Acid Spit against another target.

Claw. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) slashing damage.

Tail. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 15 (2d8 + 6) bludgeoning damage and the dragon pushes the target 10 feet away.

Acid Spit. The dragon targets a creature within 60 feet forcing it to make a DC 19 Dexterity saving throw. The creature takes 22 (4d10) acid damage on a failure or half damage on a success. A creature that fails the save also takes 5 (1d10) ongoing acid damage. A creature can use an action to end the ongoing damage.

Acid Breath (Recharge 5-6). The dragon exhales sizzling acid or necrotic energy in a 60-foot-long 5-foot-wide line. Each creature in that area makes a DC 19 Dexterity saving throw taking 31 (7d8) acid damage and 31 (7d8) necrotic damage on a failed save or half damage on a success. A creature that fails the save is blinded until the end of its next turn.

Tail Attack. When a creature the dragon can see within 10 feet hits the dragon with a melee attack, the dragon makes a tail attack against it.

The dragon can take 3 legendary actions. Only one legendary action can be used at a time and only at the end of another creatures turn. It regains spent legendary actions at the start of its turn.

Darkness. The dragon creates a 20-foot-radius sphere of magical darkness originating from a point it can see within 120 feet. Darkvision can't penetrate this darkness. The darkness lasts for 1 minute or until the dragon uses this action again.

Roar. Each creature of the dragons choice within 120 feet that can hear it makes a DC 17 Charisma saving throw. On a failure, it is frightened for 1 minute. A creature repeats the saving throw at the end of its turns, ending the effect on itself on a success. When it succeeds on a saving throw or the effect ends for it, it is immune to Roar for 24 hours.

Wing Attack. The dragon beats its wings. Each creature within 15 feet makes a DC 20 Dexterity saving throw. On a failure, it is pushed 10 feet away and knocked prone. The dragon can then fly up to half its fly speed.