Guardian Naga

Large monstrosity, lawful good

Armor Class: 18 (natural armor)
Hit Points: 127 (15d10 + 45)
Speed: 40 ft.

STR: 19 (+4)
DEX: 18 (+4)
CON: 16 (+3)
INT: 16 (+3)
WIS: 19 (+4)
CHA: 18 (+4)

Saving Throws: Dex +8, Con +7, Int +7, Wis +8, Cha +8
Damage Immunities: poison
Condition Immunities: charmed, poisoned
Senses: darkvision 60 ft., passive Perception 14
Languages: Celestial, Common
Challenge: 10 (5,900 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 an 11th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 16, +8 to hit with spell attacks), and it needs only verbal components to cast its spells. It has the following cleric spells prepared:

Cantrips (at will): mending, sacred flame, thaumaturgy

1st level (4 slots): command, cure wounds, shield of faith

2nd level (3 slots): calm emotions, hold person

3rd level (3 slots): bestow curse, clairvoyance

4th level (3 slots): banishment, freedom of movement

5th level (2 slots): flame strike, geas

6th level (1 slot): true seeing

Actions

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. Hit: 8 (1d8 + 4) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 45 (10d8) poison damage on a failed save, or half as much damage on a successful one.

Spit Poison. Ranged Weapon Attack: +8 to hit, range 15/30 ft., one creature. Hit: The target must make a DC 15 Constitution saving throw, taking 45 (10d8) poison damage on a failed save, or half as much damage on a successful one.

Running this fight? Add the guardian naga to the initiative tracker: type its name and the AC, hit points and initiative bonus fill in, and the book button shows this stat block mid-fight.