Hellspawn are bundles of maliciousness that form from the released energies of souls in Hell, a destination for those considered Spume of Creation. They are entities without souls, existing only as nightmares given flesh and being particularly hateful of anyone with a soul.
Their physical forms are extremely mutable so that one can with sufficient will shape them to requirements. Left to their own devices they are rather formless, only adhering to a particular shape if it is to their advantage. Praxis is to some extend harmful to them, if trapped there they will eventually dissipate. In earlier ages they would seek to survive by posessing a living being, with the net effect of their host being driven insane.