Legendary Resistance (5/Day). If the dracolich fails a saving throw, it can choose to succeed instead.

Magic Resistance. The dracolich has advantage on saving throws against spells and other magical effects.

Too big to die. The dracolich massive bulk grants it greater protection against smaller creatures and their toothpick-sized weapons. Any damage dealt to the dracolich from a creature two or more sizes smaller than itself must do at least 16 damage to inflict any damage, and any damage dealt is reduced by 8. 

Siege Monster. The dracolich deals double damage to objects and structures.

Font of Magic. The dracolich has 15 sorcery points, and it can as a bonus action create a spell slot by spending sorcery points equal to the spell slot level. The dracolich can as a bonus action disassemble a spell slot to regain sorcery points equal to the spell slot's level.

Metamagic. The dracolich can manipulate its magic in the following ways:

Maximized spell. The dracolich can spend sorcery points equal to the spell's level (min. 1) to maximize the damage of the spell. 

Twinned spell. Then dracolich casts a spell, it can spend sorcery points equal to the spell's level (min. 1) to twin the spell. 

Quicken Spell. The dracolich can spend 2 sorcery points to make a spell that requires an action, take a bonus action instead. 

Subtle Spell. The dracolich can spend 1 sorcery points to cast a spell without verbal and somatic components.  

Spellcasting. The dracolich is a 19th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 22, +14 to hit with spell attacks). The dracolich can cast Shield, Detect thoughts, Sending, and lightning bolt at will, and has the following wizard spells prepared:

Cantrips (at will): Fire Bolt, Frostbite, Prestidigitation, Mending, Massage  

1st level (4 slots): Charm person, Sleep, Shield, Magic missile

2nd level (3 slots): Suggestion, Hold Person, Detect thoughts, Mirror Image 

3rd level (3 slots): Lightning Bolt, Sending, Bestow Curse, Counter Spell

4th level (3 slots): Confusion, Compulsion, Charm Monster, Blight

5th level (3 slots): Synaptic Static, Negative Energy Flood, Geas, Teleportation Circle

6th level (2 slots): Mass Suggestion, Circle of Death, Otilukes Freezing Sphere

7th level (2 slots): Power word Pain, Crown of Stars, Finger of death

8th level (2 slots): Feeble mind, Power word Stun 

9th level (2 slots): Power word Kill, Wish

Multiattack. The dracolich can use its Frightful Presence, and two attacks: one with its bite and one with its claw. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 18 (2d10 + 7) piercing damage plus 5 (1d10) lightning damage.

Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 7) slashing damage.

Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 16 (2d8 + 7) bludgeoning damage.

Frightful Presence. Each creature of the dracolich's choice that is within 120 feet of the dracolich and aware of it must succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dracolich's Frightful Presence for the next 24 hours.

Lightning Breath (Recharge 5–6). The dracolich exhales lightning in a 90-foot line that is 5 feet wide. Each creature in that line must make a DC 22 Dexterity saving throw, taking 66 (12d10) lightning damage on a failed save, or half as much damage on a successful one.

The dracolich can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The dracolich regains spent legendary actions at the start of its turn.

Detect. The dracolich makes a Wisdom (Perception) check.

Tail Attack. The dracolich makes a tail attack.

Cast a spell. (Costs 2 Actions). The dracolich casts a spell.

Wing Attack (Costs 2 Actions). The dracolich beats its tattered wings. Each creature within 10 ft. of the dracolich must succeed on a DC 21 Dexterity saving throw or take 14 (2d6 + 7) bludgeoning damage and be knocked prone. After beating its wings this way, the dracolich can fly up to half its flying speed.