Guardian Naga

Large Celestial, Lawful Good

AC 18 Initiative +4 (14)
HP 136 (16d10 + 48)
Speed 40 ft., Climb 40 ft., Swim 40 ft.

Skills Arcana +11, History +11, Religion +11
Immunities Poison; Charmed, Paralyzed, Poisoned, Restrained
Senses Darkvision 60 ft.; Passive Perception 14
Languages Celestial, Common
CR 10 (XP 5,900; PB +4)

Traits

Celestial Restoration. If the naga dies, it returns to life in 1d6 days and regains all its Hit Points unless Dispel Evil and Good is cast on its remains.

Actions

Multiattack. The naga makes two Bite attacks. It can replace any attack with a use of Poisonous Spittle.

Bite. Melee Attack Roll: +8, reach 10 ft. Hit: 17 (2d12 + 4) Piercing damage plus 22 (4d10) Poison damage.

Poisonous Spittle. Constitution Saving Throw: DC 16, one creature the naga can see within 60 feet. Failure: 31 (7d8) Poison damage, and the target has the Blinded condition until the start of the naga’s next turn. Success: Half damage only.

Spellcasting. The naga casts one of the following spells, requiring no Somatic or Material components and using Wisdom as the spellcasting ability (spell save DC 16):
 At Will: Thaumaturgy
 1/Day Each: Clairvoyance, Cure Wounds (level 6 version), Flame Strike (level 6 version), Geas, True Seeing