One more for the Henry Justice Ford Monster Manual project (taking contributions through 7/31).
Armor class: As chain
Hit dice: 7
Move: crawl, medium
Attack: Breath weapon 1d8+3 (25’ range, 3x/day) or constrict 2d6/round
Appearing No.: 1
Treasure : 1000 gp, random wand or magic item (in lair)
Special: Spells, fire teleportation
Phasing in from the Plane of Fire, the Fire Naga may take an unfortunate unawares as she emerges from a hearth or forge, which she uses as her gateway between the Planes, or perhaps where she has simply been taking a respite. Fire Nagas are often summoned as spies or servants by elementalists. However, as a mercurial denizen of fire, they may also be dangerous and unpredictable, with a 10% chance/day to either turn on their summoner, or to choose to follow their own agenda. In combat, she may spit a gout of flame as an attack or defense, or constrict a foe. She will also have access to the following spells: Charm person, heat metal, pyrotechnics (each up to 2/day), and fireball (1/day). If pressed and in need of retreat, a Fire Naga may escape by teleporting through fire, either back to the elemental plane, or to another mundane fire within one mile of her current location.