My blogging companions Bruce Charlton, Frank Berger and Wm Js Tychonievich have all written some excellent and illuminating articles recently on the threefold nature of evil as defined by Rudolph Steiner, here, here and here. According to this systemisation, evil can be personified as three beings or types which are Lucifer, Ahriman and Sorath in which, borrowing Frank's definitions, Lucifer is passionate, selfish, lustful, tormented and short-term, Ahriman is cold, controlling, systematic/bureaucratic, power-hungry and mid to long term and Sorath is the pit into which they all eventually fall (unless they repent) being purely negative, destructive, hateful and desirous of annihilating both creation and, eventually, itself.
It strikes me that these can be considered as evil manifesting on the emotional, intellectual and spiritual planes which is why they can all come from Sorath originally and then all return to 'him' eventually. As our focus moves through the various levels of being we may be prone to manifesting particular sorts of evil if we distort the qualities associated with those levels, evil only ever being a distortion of good and having no authentic existence itself.
Luciferian evil is selfish above all, unable to control itself or its passions. It relates to the self as a creature of desire. It wants to be fed. I know a Luciferian type person who is abusive, angry, fiery. Lucifer is a hot evil.
Ahriman is almost the opposite to this and that is one reason we don't see it as evil now when it is the dominant evil insofar as it is the one having most impact on the world. But we still see evil primarily as a Luciferian thing, though with tinges of Ahriman and Sorath. I also know someone who is a very pure Ahriman type but he lives almost like a monk. He is highly intellectual, self-denying in terms of material goods and, by his own standards, very moral, meaning in a leftist everybody must have equal access to everything way. He is fully on board with lockdowns and would like to extend that to combat climate change. But he gives the impression of being cold and dead inside. There is a spiritual void. He is not a conventionally bad person by any means and genuinely believes he is an upright individual working for the good of humanity. But he has no time for God or the idea that we live in a created world with laws and principles that go beyond those of mathematics and physics. Ahriman is a cold evil, and if Lucifer is a corruption of quality, inasmuch as it relates to the passions and desires, then Ahriman is the idolisation of quantity. Everything can be measured and must be controlled. According to Tolkien, Sauron started off as someone who wanted to improve the world through control. His rings were chiefly means for him to do that. He seems to be a typical Ahriman figure but, and this may be the destiny of all such types who do not turn round and repent, he eventually ended up in the black hole of Sorath.
Sorath seems to be something like non-being that, as it were, comes into mental form when being is manifested in creation. It is not a thing in itself but inevitable in a dualistic world in which everything has an opposite just as light is the reality and darkness is merely the absence of light. So, Sorath is not actually real but gains a certain reality given to it by conscious beings becoming conscious of their own consciousness and freedom to deny what is. Sorath is the void, a cosmic dustbin into which everything goes that denies God. Neither hot nor cold but dead. As life necessarily implies death in the world but life is the reality so Sorath is the non-reality that arises as a potential when reality becomes actual.
Steiner apparently thought that Lucifer and Ahriman served an evolutionary purpose but I disagree. I think they are just distortions of the good, possible because God has given us the freedom to deny divine reality which freedom he has given us in order that we might consciously choose divine reality and so bring about a creation of active good rather than simple sterile perfection.