Spirit Naga

Large monstrosity, chaotic evil

Armor Class 15 (natural armor)
Hit Points 75 (10d10 + 20)
Speed 40 ft.

Saving Throws Dex +6, Con +5, Wis +5, Cha +6
Damage Immunities poison
Condition Immunities charmed, poisoned
Senses darkvision 60 ft., passive Perception 12
Languages Abyssal, Common
Challenge 8 (3,900 XP)

Rejuvenation. If it dies, the naga returns to life in 1d6 days and regains all its hit points. Only a wish spell can prevent this trait from functioning.
Spellcasting. The naga is a 10th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 14, +6 to hit with spell attacks), and it needs only verbal components to cast its spells. It has the following wizard spells prepared:
Cantrips (at will): mage hand, minor illusion, ray of frost
1st level (4 slots): charm person, detect magic, sleep
2nd level (3 slots): detect thoughts, hold person
3rd level (3 slots): lightning bolt, water breathing
4th level (3 slots): blight, dimension door
5th level (2 slots): dominate person

Actions

Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., one creature. Hit: 7 (1d6 + 4) piercing damage, and the target must make a DC 13 Constitution saving throw, taking 31 (7d8) poison damage on a failed save, or half as much damage on a successful one.