Guardian Naga

Large monstrosity, lawful good

Armor Class 18 (natural armour)

Hit Points 127 ( 15d10+45 )

Speed 40ft

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

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

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.

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.