Guardian Naga

5e compatible shield

Large monstrosity, lawful good

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

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

Saving Throws Dex +8, Con +7, Int +7, Wis +8, Cha +8
Skills 
Damage Resistances 
Damage Immunities poison
Condition Immunities charmed, poisoned
Senses darkvision 60 ft., passive Perception 14
Languages Celestial, Common
Challenge 10 (5900 XP)

Rejuvenation. If it dies, the naga returns to life in 1d6 days and regains all its hit points. Only a ““ 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): ““, ““, ““ 1st level (4 slots): ““, ““, ““ 2nd level (3 slots) : ““, ““ 3rd level (3 slots): ““, ““ 4th level (3 slots): ““, ““ 5th level (2 slots): ““, ““ 6th level (1 slot): ““

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.