Adult Black Dracolich

Amphibious. The dracolich can breathe air and water.

Legendary Resistance (3/Day, or 4/Day in Lair). If the dracolich fails a saving throw, it can choose to succeed instead.

Soul Gem. The dracolich has a magical gem. If the dracolich is destroyed while the gem is on the same plane of existence as it, the dracolich gains a new body in 1d20 days, regaining all its Hit Points and appearing within 5 feet of the gem.

The gem is a Tiny object that has AC 20; HP 50; and Immunity to Necrotic, Poison, and Psychic damage. The gem regains all its Hit Points at the end of every turn, but it turns to dust if reduced to 0 Hit Points. If the gem is destroyed, the dracolich can create a new one by completing an 8-hour ritual using a gem worth 1,000+ GP and by expending 5,000 GP, which the ritual consumes

Multiattack. The dracolich makes three Rend attacks. It can replace one attack with a use of Spellcasting to cast Melf’s Acid Arrow (level 3 version).

Rend. Melee Attack Roll: +12, reach 10 ft. Hit: 13 (2d6 + 6) Slashing damage plus 4 (1d8) Acid damage.

Acid Breath (Recharge 6). Dexterity Saving Throw: DC 20, each creature in a 60-foot-long, 5-foot-wide Line. Failure: 54 (12d8) Acid damage. Success: Half damage.

Necrotic Breath (Recharge 6). Dexterity Saving Throw: DC 20, each creature in a 60-foot Cone. Failure: 52 (8d12) Necrotic damage. Success: Half damage.

Spellcasting. The dracolich casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 20, +11 to hit with spell attacks):

At Will: Detect Magic, Fear, Melf’s Acid Arrow (level 3 version), Ray of Sickness (level 2 version).

3/Day Each: Dimension Door, Greater Invisibility, Dispel Magic (Level 5 version).

1/Day Each: Speak with Dead, Vitriolic Sphere, Create Undead (Level 8 version), Finger of Death, Power Word Stun flavoured as unfathomable pain.

Shadow Step (Recharge 4-6). The dracolich is briefly shrouded in shadow and teleports from one area of Darkness to another it can see within 120 feet.

Shield (3/day). The dracolich uses Spellcasting to cast the Shield spell.

Counterspell (3/day). The dracolich uses Spellcasting to cast Counterspell (Level 5 version).

Legendary Action Uses: 3 (4 in Lair). Immediately after another creature's turn , the dracolich can expend a use to take one of the following actions. The dragon regains all expended uses at the start of each its turns.

Cloud of Rot. Dexterity Saving Throw: DC 20, one creature the dracolich can see within 120 feet. Failure: 22 (4d10) Necrotic damage, and the target's hit point maximum is reduced by half the damage taken. Failure or Success: The dragon can’t take this action again until the start of its next turn.

Frightful Presence. The dracolich uses Spellcasting to cast Fear. The dragon can’t take this action again until the start of its next turn.

Sickening Ray. The dracolich uses Spellcasting to cast Ray of Sickness (level 2 version).

Pounce. The dracolich can move up to half its Speed, and it makes one Rend attack.