Abalach-Re

Armor Class: 18 (natural armor) Hit Points: 300 (24d8 + 192) Speed: 30 ft.

STR: 10 (+0)
DEX: 16 (+3)
CON: 14 (+2)
INT: 20 (+5)
WIS: 12 (+1)
CHA: 24 (+7)

Saving Throws: Dex +10, Con +9, Int +13, Wis +7, Cha +15
Skills: Arcana +18, Deception +15, Insight +7, Persuasion +15
Damage Resistances: necrotic
Senses: darkvision 120 ft., passive Perception 11
Languages: Common, Elvish, Draconic

Spellcasting: Abalach-Re is a 20th-level spellcaster. Her spellcasting ability is Charisma (spell save DC 23, +15 to hit with spell attacks). She has the following sorcerer spells prepared:

Cantrips (at will): chill touch, fire bolt, mage hand, ray of frost, shocking grasp
1st level (4 slots): mage armor, magic missile, shield
2nd level (3 slots): detect thoughts, mirror image, misty step
3rd level (3 slots): counterspell, fireball, lightning bolt
4th level (3 slots): blight, dimension door
5th level (3 slots): cloudkill, dominate person
6th level (2 slots): chain lightning, disintegrate
7th level (2 slots): finger of death, plane shift
8th level (1 slot): dominate monster, power word stun
9th level (1 slot): meteor swarm, power word kill

Defiler Magic (Recharge 6): As a bonus action, Abalach-Re can expend a spell slot to increase the damage of her next spell by 2d8 per level of the spell slot expended. If she does so, the spell also leaves behind desolated terrain in a 30-foot radius centered on the target. The terrain remains desolated for 1 minute, causing it to become difficult terrain, and any creature that starts its turn in the area takes 1d6 necrotic damage.

Spellcasting Mastery: Abalach-Re can use her reaction to counterspell a spell targeting her or make a saving throw against a spell that affects her.

Sorcerous Restoration: Once per day, as a bonus action, Abalach-Re can regain a number of expended sorcery points equal to her Charisma modifier (7).

Actions

Quarterstaff: Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) bludgeoning damage.

Legendary Actions

Abalach-Re 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. She regains spent legendary actions at the start of her turn.

Defiling Pulse: Abalach-Re causes desolation in a 20-foot radius centered on herself. Each creature in that area takes 6d6 necrotic damage and the area becomes for 1 minute.

Counterspell: Abalach-Re casts counterspell.

Teleport: Abalach-Re magically teleports, along with any equipment she is wearing or carrying, up to 120 feet to an unoccupied space she can see.

Legendary Resistance (4/Day): If Abalach-Re fails a saving throw, she can choose to succeed instead.