Adult Kendermore Blue Dragon-Lich

Legendary Resistance (4/Day). If the dragon fails a saving throw, it can choose to succeed instead.

 Turn Resistance Aura. The dragon-lich and all Undead within 15 feet of it have advantage on saving throws against any effect that turns undead.

Hideous Telepathy. When the dragon-lich talks to a creature using its telepathy for the first time, the creature must succeed on a DC 17 Constitution saving throw or take 2 (1d4) psychic or necrotic damage (dragon-lich's choice) and have disadvantage on all saving throws, ability checks and attack rolls until the end of the next round. A creature that succeeds on the saving throw once is immune to the dragon-lich's Hideous Telepathy for 1 hour.

Rejuvenation. If it has a phylactery, a destroyed dragon-lich gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the phylactery.

Regeneration. The dragon-lich regains 25 hit points at the start of each of its turns if it has lost any amount of hit points.

Semi-Immortal Nature. The dragon-lich dosen't require food, air, or drink and it has advantage on saving throws against spells with the (chronomancy) tag.

Draconic Nature. The Dragon-Lich is considered to be both an Undead and a Dragon rather than just an Undead when being affected by spells or other sources.

Necromancy Proficiency. Whenever the dragon-lich casts a Necromancy spell, it can choose to cast the spell at the same level it normally is but using a spell slot of up to two levels lower (except cantrip level). For example, if the dragon-lich wanted to cast animate dead, it could expend a spell slot of 2nd or 1st level instead of 3rd level to cast the spell at the same power it normally is.

Lifeforce Spells. Whenever the dragon-lich casts a spell that deals necrotic damage or the damage type dealt by its breath weapon, it can choose to sacrifice an amount of hit points in order to increase the amount of damage dealt by the spell by half the amount of hit points sacrificed. Additionally, if the dragon-lich has no spell slots remaining of a certain level, it can choose to sacrifice an amount of hit points equal to the level of the spell slot to instantely regain 1 spell slot of that level as a bonus action.

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

Bite. Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 23 (4d6 + 9) piercing damage + 13 (2d12) lightning damage + 2 (1d4) necrotic damage.

Claw. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 20 (2d10 + 9) slashing damage + 10 (3d6) cold damage and the target must succeed on a DC 17 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. 

Tail. Melee Weapon Attack: +15 to hit, reach 20 ft., one target. Hit: 21 (2d12 + 9) bludgeoning damage + 2 (1d4) necrotic or cold damage (dragon-lich's choice).

Horn. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 18 (2d8 + 9) piercing damage + 9 (2d8) lightning damage + 3 (1d6) necrotic damage.

Frightful Presence. Each creature of the dragon's choice that is within 120 feet of the dragon 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 dragon's Frightful Presence for the next 24 hours.

Lightning Breath (Recharge 5–6). The dragon exhales lightning in a 95-­foot line that is 10 feet wide. Each creature in that line must make a DC 22 Dexterity saving throw, taking 93 (17d10) lightning damage on a failed save, or half as much damage on a successful one.

Innate Spellcasting. The dragon's spellcasting ability is Charisma (spell save DC 20, +13 to hit with spell attacks). The dragon can innately cast the following spells, requiring only verbal components:

At Will: thaumaturgy, lightning lure, magic missile, create or destroy water, shield

2/day each: major image, thunder step, slow, arcane eye, wall of stone, telekinesis, forcecage

4/day: chain lightning, programmed illusion, etherealness

Spellcasting. The dragon-lich's spellcasting ability is Intelligence (spell save DC 24, +18 to hit with spell attacks). The dragon-lich has the following wizard spells prepared:

Cantrips (at will): mage hand, prestidigitation, ray of frost, shape water

1st level (4 slots): detect magic, magic missile, shield, thunderwave, unseen servant

2nd level (4 slots): acid arrow, detect thoughts, invisibility, mirror image

3rd level (3 slots): animate dead, counterspell, dispel magic, fireball

4th level (3 slots): blight, dimension door, spirit of death

5th level (3 slots): cloudkill, scrying, seeming

6th level (2 slots): disintegrate, globe of invulnerability

7th level (2 slots): finger of death, plane shift

8th level (1 slot): dominate monster, power word stun

9th level (1 slot): power word kill

10th level (1 slot): doom

The dragon-lich 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 dragon-lich regains spent legendary actions at the start of its turn.

Detect. The dragon-lich makes a Wisdom (Perception) check.

Swift Attack. The dragon-lich makes a tail or claw attack.

Minor Spell. The dragon-lich casts a cantrip, 1st, or 2nd level spell.

Wing Attack (Costs 2 Actions). The dragon-lich beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 23 Dexterity saving throw or take 16 (2d6 + 9) bludgeoning damage + 2 (1d4) necrotic damage and be knocked prone. The dragon can then fly up to half its flying speed.

Disrupt Life (Costs 3 Actions). Each non-undead creature within 25 feet of the dragon-lich must make a DC 17 Constitution saving throw against this magic, taking 21 (6d6) necrotic damage on a failed save, or half as much damage on a successful one.