Flame Snake, Greater (CR 16)

Huge Magical Beast (Fire)
Alignment: Usually evil (any)
Initiative: +7 (+3 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., low-light vision, scent, Listen +14, and Spot +14

AC: 29 (-2 size, +3 Dex, +18 natural), touch 11, flat-footed 26
Hit Dice: 17d10+85 (178 hp); DR: 15/magic
Fort +15, Ref +13, Will +7
Speed: 60 ft., climb 50 ft.
Space: 15 ft./15 ft. (coiled)
Base Attack +17; Grapple +33
Attack: Bite +24 melee
Full Attack: Bite +24 melee and crush +19 melee and tail spike +18 melee
Damage: Bite 2d8+8 plus 1d6 fire plus 1d6 negative energy plus poison, crush 1d8+4 plus 1d6 fire plus 1d6 negative energy, tail spike 1d6+4 plus 1d6 fire plus 1d6 negative energy
Special Attacks/Actions: Breath weapon, constrict 4d6+12 plus 1d6 fire plus 1d6 negative energy death throes, fiery aura, fiery poison, hear, improved grab, negative energy, spell-like abilities, swallow whole
Abilities: Str 27, Dex 17, Con 20, Int 11, Wis 14, Cha 16
Special Qualities: fast healing 5, fire subtype, SR 27, uncanny dodge
Feats: Alertness; Cleave; Improved Initiative; Power Attack; Weapon Focus (bite); Weapon Focus (Crush)
Skills: Climb +16, Hide -5, Listen +14, Move Silently +13, Search +10, and Spot +14
Advancement: 18-24 HD (Huge); 25-51 HD (Gargantuan)
Climate/Terrain: Any land and underground
Organization: Solitary, pair, or clutch (3-6)
Treasure/Possessions: Standard

Source: Fiend Folio

All flame snakes have some abilities in common.

Heat (Ex): A flame snake generates so much heat that its mere touch deals additional fire damage. This damage varies by subrace.

Fire Subtype (Ex): A flame snake is immune to fire damage. It takes half again as much (+50%) damage as normal from cold, regardless of whether a saving throw is allowed, or if the save is a success or a failure.

Scent (Ex): A flame snake can detect approaching enemies, sniff our hidden foes, and track by sense of smell.

Skills: Flame snakes have a +8 racial bonus on Climb checks and can always choose to take 10 on Climb checks, even if rushed or threatened.

Greater flame snakes use their breath weapons early and often. They are also constantly hungry and make frequent use of their swallow whole ability while waiting for their breath weapon to recharge. Against particularly challenging foes, they don't hesitate to employ their spell-like abilities, but they know that their best tactic is to stay close to their opponents and allow their fiery aura to wear their foes down.

Breath Weapon (Su): Every 1d4 rounds, a greater flame snake can unleash a 50-foot cone of dark fire. A Reflex save (DC 23) halves the damage. The breath weapon deals 12d6 points of damage, half of which is fire damage and the other half of which is negative energy damage.

Constrict (Ex): With a successful grapple check, a greater flame snake can constrict a grabbed opponent, dealing 4d6+12 points of bludgeoning damage, 1d6 points of fire damage, and 1d6 points of negative energy damage.

Death Throes (Ex): When slain, a greater flame snake explodes in a blinding flash of fiery light that deals 30 points of damage (15 points fire, 15 points negative energy) to everything within iso feet. A Reflex save (DC 23) halves the damage.

Fiery Aura (Ex): Merely being in the presence of a greater flame snake is damaging. Any creature within is feet of a greater flame snake automatically takes 1d6 points of fire damage.

Fiery Poison (Ex): A greater flame snake delivers its poison (Fort DC 26 negates) with each successful bite attack. Initial and secondary damage are the same (1d4 Str). In addition, if the save fails, the greater flame snake's poison burns its victim from the inside as it courses through the opponent's body. Each round the poison remains in a victim's bloodstream (maximum 10 rounds), it deals 4 points of fire damage (no save). This includes the round in which the victim was bitten.

Improved Grab (Ex): If a greater flame snake hits an opponent that is at least one size category smaller than itself with a bite attack, it deals normal damage and attempts to start a grapple as a free action without provoking an attack of opportunity (grapple bonus +33). If it gets a hold, it can swallow the opponent on its next successful grapple check. Alternatively, the greater flame snake has the option to conduct the grapple normally, or simply use its bite to hold the opponent (-20 penalty on grapple check, but the greater flame snake is not considered grappled). In either case, each successful grapple check it makes during successive rounds automatically deals bite damage.

Negative Energy (Su): A greater flame snake's dark origins provide it with the ability to deal negative energy damage with most of its attacks. See the descriptions of individual special attacks and special qualities for details.

Swallow Whole (Ex): A greater flame snake can swallow a single creature that is at least two size categories smaller than itself by making a successful grapple check (grapple bonus +33), provided it already has that opponent in its maw (see Improved Grab, above). Once inside the greater flame snake, the opponent takes 2d6+13 points of crushing damage, 1d4 points of fire damage, and 1d4 points of negative energy damage per round from the flame snake's stomach. A successful grapple check allows the swallowed creature to climb out of the stomach and return to the greater flame snake's maw, where another successful grapple check is needed to get free. Alternatively, a swallowed creature can try to cut its way out with either claws or a light piercing or slashing weapon. Dealing a total of at least 20 points of damage to the stomach (AC 19) in this way creates an opening large enough to permit escape. Once a single swallowed creature exits, muscular action closes the hole; thus, another swallowed opponent must cut its own way out. A greater flame snake's stomach can hold 2 Large, 4 Medium-size, or 11 Small or smaller opponents.

Spell-like Abilities: 3/day - fireball, fire shield (warm shield only); 1/day - firestorm, flame strike, maximized fireball. Caster level 16th; save DC 13 + spell level.

Fast Healing (Ex): A greater flame snake regains lost hit points at the rate of 5 per round. Fast healing does not restore hit points lost from starvation, thirst, or suffocation, and it does not allow a greater flame snake to regrow or reattach lost body parts.

Uncanny Dodge (Ex): A greater flame snake retains its Dexterity bonus to Armor Class even when flat-footed or struck by an invisible attacker, and it cannot be flanked except by a rogue of at least 21st level.

All three species of flame snake use similar tactics in battle. They prefer to bite their opponents and then allow their venom to run its course. The smaller, less intelligent flame snakes repeat this tactic until their opponents are brought down; the more intelligent varieties have other abilities at their disposal. The flame snake's fiery venom is one of its most feared weapons. The fierce, burning agony the toxin causes sometimes drops would-be intruders even after they have attempted to flee from the burning creatures.

Fire Subtype

A creature with the fire subtype has immunity to fire. It has vulnerability to cold, which means it takes half again as much (+50%) damage as normal from cold, regardless of whether a saving throw is allowed, or if the save is a success or failure.