Aspect of Mephistopheles (CR 24)

Large Outsider (Baatezu, Evil, Extraplanar, and Lawful)
Alignment: Lawful Evil
Initiative: +12(+8 Dex, +4 Improved Initiative); Senses: see in darkness, Listen +35, and Spot +38
Languages: Celestial, Common, Draconic, Infernal; telepathy 100 ft.

AC: 47 (-1 size, +8 Dex, +23 natural, +2 armor and/or shield, + 5 deflection), touch 22, flat-footed 39
Hit Dice: 30d8+240 (375 hp); DR: 20/good and silver
Fort +29, Ref +29, Will +31
Speed: 40 ft. and Fly 100 ft. (average)
Space: 15 ft.; Reach 10 ft. (20 ft. with ranseur)
Base Attack +30; Grapple +41
Attack: Melee: +5 flaming burst icy burst ranseur +41/+36/+31/+26
Damage: +5 flaming burst icy burst ranseur 2d6+15/19-20/x3 plus 1d6 cold and 1d6 fire [plus 2d10 cold and 2d10 fire on a critical hit]
Special Attacks/Actions: evoke hellfire, summon baatezu
Attack Options: Violate Spell-Like Ability
Abilities: Str 25, Dex 27, Con 26, Int 27, Wis 31, Cha 28
Special Abilities: evoke hellfire, flames of hell, spell-like abilities, summon baatezu
Special Qualities: regeneration 8; Immune: cold, fire, poison; Resist: acid 10; SR 37
Feats: Craft Wondrous Item, Dark Speech, Empower Spell, Improved Critical (ranseur), Improved Initiative, Negotiator, Scribe Scroll, Spell Focus (evocation), Spell Penetration, Violate Spell (fireball), Violate Spell-Like Ability (fireball),
Skills: Appraise +8 (+10 alchemical items), Balance +24, Bluff +42, Concentration +31, Craft (alchemy) +28, Diplomacy +48, Disguise +19 (+21 acting), Forgery +41, Gather Information +29, Hide +37, Intimidate +44, Jump +44, Knowledge (arcana) +28, Knowledge (history) +28, Knowledge (the planes) +28, Listen +35, Move Silently+33, Search +28, Sense Motive +45, Spellcraft +35, Spot +38, Survival +10 (+12 on other planes or follow tracks), and Tumble +38
Advancement:
Climate/Terrain: Cania (8th layer of Baator)
Organization:
Treasure/Possessions:

Source: Fiendish Codex II

An aspect of Mephistopheles's natural weapons, as well as weapons it wields, are treated as evil-aligned and lawful-align for the purpose of overcoming damage reduction.

Fire Shield (Su): An aspect of Mephistopheles is continuously sheathed in flame, as the fire shield spell (caster level 10th. The save DC is Charisma-based.

Fireball (Sp): Once per day an aspect of Mephistopheles can create a fireball effect (caster level 10th, Reflex DC 19 half). The save DC is Charisma-based.

Baatezu Subtype

Many devils belong to the race of evil outsiders known as the baatezu.

Traits: A baatezu possesses the following traits (unless otherwise noted in a creature's entry).

Evil Subtype

A subtype usually applied only to outsiders native to the evil-aligned Outer Planes. Evil outsiders are also called fiends. Most creatures that have this subtype also have evil alignments; however, if their alignments change, they still retain the subtype. Any effect that depends on alignment affects a creature with this subtype as if the creature has an evil alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the evil subtype overcomes damage reduction as if its natural weapons and any weapons it wields were evil-aligned (see Damage Reduction).

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.

Lawful Subtype

A subtype usually applied only to outsiders native to the lawful-aligned Outer Planes. Most creatures that have this subtype also have lawful alignments; however, if their alignments change, they still retain the subtype. Any effect that depends on alignment affects a creature with this subtype as if the creature has a lawful alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the lawful subtype overcomes damage reduction as if its natural weapons and any weapons it wields were lawful-aligned (see Damage Reduction).