Hellfire engine

Hellfire engines were enormous constructs created in the Nine Hells by devils to bring destruction to their foes en masse. Hybrids of magic and machinery, they were among the most dangerous of the abominations tied to the planar energy known as hellfire.
==Description==
Hellfire engines typically stood about tall and weighed . The automatons took many forms, (a known design included a humanoid, bearded man with stag horns an impossibly wide mouth), but they had in common their power source. White-hot light could be seen emanating from the inferno within their bodies.
==Behavior==
Hellfire engines were semi-autonomous, possessing basic awareness but lacking intelligence and identity to a degree bordering on absence. They could respond to the simple commands of their creator (as with golems) or another entity they were ordered to obey and were incapable of subtlety or deception. However, their drive to destroy could urge them to run rampant in a berserk frenzy. Whether or not they qualified as truly lawful evil beings or just neutral ones seemed inconsistent. 
==Abilities==
The most noteworthy trait of hellfire engines is their namesake; created by Mephistopheles, the infernal flames were not truly fire at all, but a planar energy derived from Hell itself that took the form of flame. It was hotter than any mundane fire and could burn through not only the hardest known substances, but the very souls of those unfortunate enough to be subject to it. With this, no known creature in the cosmos could resist the terrible attacks of hellfire engines. It infused their attacks, could be spew out in gouts, and radiated out from their bodies such that just touching or striking them was a potentially lethal prospect. 
Hellfire engines were also known to be outfitted in what were known as "hellfire weapons". These included "bonemelt sprayers" which drenched the enemy in burning, acidic fuel, "lightning flails" which electrocuted those nearby those the flail actually struck, and "thunder cannons", which devastated the area the engine shot at with terrible force. Though not every weapon made apparent use of hellfire, death to any of them would condemn a victim to existence in the infernal legions. Unless quickly saved, their soul would rise as a lemure from the River Styx in Avernus within a few hours, and from there could only be rescued with a wish spell, or a true resurrection spell after killing the lemure. Constructs, devils and demons were known to be immune to this effect, although the archdevils would love to find a way to modify the magic such that the lattermost group were not.
Even without their hellfire and many potential ordinances, hellfire engines were still dangerous and destructive weapons. They were incredibly powerful, able to stampede over even larger creatures and leave them crushed and immobile beneath their mass. Their bodies were made of cold iron, and incredibly durable and difficult to damage without magical, good-aligned, silver, and/or adamantine weapons. Their forms were immutable, and their were immune and resistant to all manner of powers, effects and conditions that varied based on reports.
Among the only known weaknesses of hellfire engines was that, as entities of fire and steel, they were susceptible to the cold (at the very least when compared to their various immunities) and had a tendency to explode when destroyed.
==Combat==
If ordered to fight, hellfire engines were reported to open combat by spraying the area with hellfire before moving forward and engaging in melee.
==Society==
Hellfire engines existed to destroy enemies in waves. They were tools of war that anchored armies and granted impressive artillery to the infernal military. However, though constructed for use in the Blood War, they served their creator, Mephistopheles, when not on loan to the Lord of the First for use in stemming the constant tides of demons. In this domestic capacity they were his guards, or just symbols of his power and prestige. Many devils speculated that, in addition to annihilating legions of devils as well as demons, hellfire engines were a deterrent against treachery from Mephistopheles' dukes.
Hellfire engines were normally encountered individually, where they functioned as guardians for powerful devils (though typically not for things such as vaults and hoards, as they were much too specialized weapons of war for such a role). Devilish generals, such as amnizu, typically kept them in reserve until they were needed to repel invading demons or crusading mortals. They might also be found amidst a squadron of other devils as part of a strike force, such as ten barbazu, six orthons, or six steel devils.
==Ecology==
The resources required to create hellfire engines were scarce. They were assembled using their own weight's worth of cold iron, which was bathed in the blood of celestials and then polished with a rare blend of Hell-endemic brimstone, sulfur and acids worth at least 80,000 gold pieces at least. The creation process required great proficiency in armor or weapon smithing, as well as the ability to craft constructs. Even more harrowing than the mundane aspect of forging the engine was the magical knowledge needed. Only an exceedingly powerful spellcaster of the correct moral and ethical outlook (lawful evil) with mastery over hellfire and access to spells such as limited wish had the ability to construct them. All these restrictions put together meant that hellfire engines were, fortunately, rare.
==Appendix==
===See Also===
* Infernal war machine
===References===