The Forgefiend is a Daemon Engine wrought for slaughter at range, a hulking centauroid war-machine forged by the Warpsmiths of the Dark Mechanicum. It stands upon four heavy legs, its arms replaced entirely by great weapon-mounts, and within its rune-scribed hull writhes a daemon dragged screaming from the Warp and shackled against its will. Unlike a warrior who accepts a daemon willingly, the Forgefiend's tenant is a prisoner, and its rage at its captivity is turned outward upon whatever its masters set before it.
Its guns are like nothing forged in an honest manufactorum. The Forgefiend carries either a trio of ectoplasma cannons or a pair of hades autocannons, and neither fires ordinary shot. Instead the weapons spit searing phosphor rounds extruded from the convulsing cables that churn within the engine's belly, while hidden organic tracts feed steaming, large-bore shells into its chambers as though the machine were digesting its own ammunition. Every round it looses carries the taint of daemonic flame, and the Forgefiend can flay a battle line to ruin from clear across the field.
Bound though it is, the daemon within is never truly tamed. It strains constantly against the wards that hold it, and only the will of a Warpsmith keeps it aimed at the foe rather than turned upon its own creators. When loosed, it hammers the enemy with relentless, hateful fire, roaring its fury with every shot, a captive god of war venting its endless anguish upon all who dare stand before it.