Ancient Black Dracolich: Dyrian, Taker of Life

Legendary Resistance (2/Day). If Dyrian fails a saving throw, it can choose to succeed instead.

Spellcasting  Dyrian is an 20th level spellcaster, Dracolich. Its spell casting ability is Intelligence (spell save DC 20, +12 to hit with spell attacks). Dyrian has the following wizard spells prepared:

Cantrips (at will): mage hand, ray of frost, acid splash

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

2nd level (3 slots): acid arrow, invisibility, mirror image, hold person

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

4th level (3 slots): blight, banishment

5th level (3 slots): cloudkill, scrying

6th level (2 slots): disintegrate, chain lightning

7th level (2 slots): finger of death, firestorm*

8th level (2 slots): dominate monster, power word stun

9th level (2 slots): power word kill, weird

*These spells deal acid damage instead of the listed damage type. Functioning as an extension of the Dyrian's natural damage type.

Multiattack. Dyrian can make three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) piercing damage plus 9 (2d8) acid damage.

Claw. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +13 to hit, reach 20 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.

Breath Weapon (Recharge 6) Dyrian exhales acid in a 90-foot line that is 10 feet wide. Each creature in that line must make a DC 20 Dexterity saving throw. On a failed save, the creature takes 54 (12d8) acid damage and 13 (3d8) necrotic damage, reducing the creature's maximum hit points by the necrotic damage taken. The creature takes half as much damage and does not have their hit points reduced on a successful save.

Dyrian can take 2 legendary actions, regaining spent legendary actions at the start of its turn.

Bite Attack. Dyrian makes a bite attack.

Wing Attack (Costs 2 Actions). Dyrian beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 23 Dexterity saving throw or take 15 (2d6 + 8) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

In addition to Legendary Actions, Dyrian has a Legendary Turn.

Legendary Turn. Dyrian gains a second initiative count of plus or minus 10 to its original initiative role. This second legendary turn consists of a full movement, action, bonus action, and regains any spent reactions or legendary actions. However, at least 1 player character must have an initiative between the Dyrian's initiative and legendary action.