Hellfire Engine (CR 19)
Initiative: -1(Dex); Senses: darkvision 60 ft. and low-light vision
AC: 37 (-2 size, -1 Dex, +30 natural), touch 7, flat-footed 38
Hit Dice: 44d10+40 (282 hp); DR: 15/adamantine and good
Fort +14, Ref +13, Will +14
Speed: 20 ft.
Space: 15 ft.; Reach 15 ft.
Base Attack +33; Grapple +51
Attack: Melee*: 2 slams + 30 each (2d6+21 plus 6d6 hellfire (*includes adjustments for Power Attack feat))
Special Attacks/Actions: breath weapon
Attack Options: Power Attack
Abilities: Str 30, Dex 8, Con -, Int -, Wis 11, Cha 1
Special Abilities: breath weapon, death throes, hellfire slams; Immunities: construct immunities; Resist acid 10,electricity 10, sonic 10;
Special Qualities: cold iron body, construct traits, hellfire shield
Feats: Power Attack (b),
Advancement: 45-48 HD (Huge); 49-98 HD (Gargantuan)
Climate/Terrain: Native to Baator, found in any land and underground
Organization: Individual or squad (Engine with 10 bearded devils or 6 orthons or 6 steel devils)
Fiendish Codex II
Breath Weapon (Su): 60-ft. cone, once every 1d4 rounds, 20d10 damage, Reflex DC 32 half. The save DC is Constitution-based.
Cold Iron Body (Ex): A hellfire engine is constructed entirely out of cold iron. Its slam attacks count as cold iron for the purpose of overcoming damage reduction.
Death Throes (Ex): When destroyed, a hellfire engine explodes in a 60-foot-radius burst that deals 20d10 points of damage to everything in the area (Reflex DC 32 half). The save DC is Constitution-based.
Hellfire Shield (Su): A hellfire engine's body casts of tremendous amounts of energy. Any creature that strikes or touches a hellfire engine with an armed or unarmed melee attack, or that grapples a hellfire engine, automatically takes 6d6 points of damage. A creature takes damage from this ability only once per turn.
Hellfire Slams (Su): A hellfire engine deals an extra 6d6 points of hellfire damage with its slam attacks.
Hellfire engines are infernal constructs constructed as artillery for use in the Blood War.