Well first, I'd like to show you something I use when I make villains for D&D. The
Villain Workshop, by Rich Burlew, creator of the Order of the Stick webcomic. It doesn't strictly deal with "how to be evil," but it DOES deal with how to make a well-rounded villain with depth and character.
As for killing a God (setting aside whether that's 'possible' in game, since that's up to the big bosses, so we'll just assume for sake of this discussion that it's the journey/attempt that count, not whether you succeed), I don't even know if quite everyone would call you evil for that. People in Ravok might praise you for taking down one of Rhysol's 'rivals' (I'm not sure if Rhysol and Lhex specifically get along or dislike each other, but it's just an example). And someone like Tock wouldn't see it as different than any normal murder.
As for your question, "What nearly everyone would consider evil?" Let's also assume that there's always going to be some individuals outside the bell curve that will be exceptions. Nothing is 100%. But if, say, 80-90% of people say that's evil, then it would definitely count as evil. That way we can discard the stray exceptions, the complete lunatics, and others whose views don't represent society as a whole.
So by that definition, what would I think counts as 'nearly' universal evil?
I'll make a general list of things that I
think would count. I'm not TOO familiar with cities like, say, Lhavit, Alvadas, or Zinrah, so there might be exceptions to these. But based on the 80-90% rule, I think we could discount a whole city if need be (for example, there's only 900 Symenestra in the world, most of them in Kalinor. Their views are surely VASTLY different from human morals, but since 900 people in the species represents less than 1% of the world population, we could discard them for statistical purposes).
So based on that, here's my basic list:
1. "Mass slaughter without purpose." This goes beyond simply murder, since plenty of places, like Sunberth, you can get away with murder just fine as long as you are justified (even if the justification is as simple as getting into a verbal argument and being pissed off enough to shank a bitch, yo). But even in the Sunberth player's guide, they say 'hapless slaughter' will cause the mob to revolt. Furthermore, while some people can be rallied to a 'cause' that leads to mass slaughter (like real life examples of the crusades or the holocaust), you'll only have 'support' in that if you convince people there's a reason for it. Most people might see it as evil, but if you rallied an entire city to a religious war, ethic cleansing, or something like that, then your supporters don't think it's evil. Even if we consider that you need to basically brainwash people with propaganda for that support, that's still a certain (twisted and deranged) percentage of the population that thinks it's 'for a good cause'.
But if there is no purpose? Or, let's say, no purpose that isn't blatantly and obviously purely selfish? That makes a difference when you're talking about evil being a matter of 'perspective'. Perspective could be used to convince a group of people something is for a good cause, but if you're blatantly, openly declaring that this isn't to further a cause, this isn't to achieve some religious ideal (like how Rhysol's followers, in their fanaticism, don't think they're evil), and this isn't for anything other than your personal power, then odds are everyone will say you're evil.
To further this idea of "Mass slaughter without purpose," I'd say you need to equally kill any race, species, religion, or sex, as long as they're in your way (or just to experiment, or just for fun, or whatever). Then no one can take sides, no one can say "Well, she's only killing
kelvics, who needs 'em?" If you kill members of every race, all races would see you as evil. If you kill people from any city, all nations could see you as evil. And so forth.
I think that about covers that. So what else can I call "overall evil"?
2. "Unrelenting cruelty to children." Children are precious. While some people will beat their kids, or be okay with child labor, and so forth, I think that in most societies there's a certain line with kids that once you cross it, that's that. Again, this would need to cross all races and cultures, since racism could overpower some people's morals and make them think it's okay ("If she kills all the Zith babies, that's fine, wipe the species out before they grow up to be evil monsters!").
This can, of course, be hard to write. Tock murdered a single child in a thread, "for a good cause," and it was one of the hardest scenes I ever wrote. So actually playing out mass murder, torture, magical experimentation, and so forth on children might not be a line you want to cross. But, from a purely philosophical perspective on "evil," this one tends to be up there in all cultures.
3. "Treason, blasphemy, and sacrilege." Another one that needs to be "universal" to work as evil. Followers of Rhysol would be fine with you burning down a temple to one of the 'good' Gods, but would hate you for burning down
their temple. Since every region has different deities they primarily worship, you'd basically need to violate all of them. And to cover the non-religious people, you'd want to add in violating the laws, customs, and traditions of cities themselves. Burn flags, destroy monuments, ruin places of tradition and worship. Show no respect for any body of authority, be it political, religious, or cultural. Declare that no one has authority over you, be it the temples of the Gods, the Sailor's Guild of Zeltiva, the 'high and mighty' Knights of Syliras, or the Svefra and their "Nal'lyeo". Be an equal opportunity discriminator, and tear down anything that
anyone holds dear. Especially if you're doing it not to start a revolution, not to educate people about a cause, not to encourage people to think for themselves, but simply because you hate these pathetic semblances of authority and think they deserve to be destroyed just because they exist.
Of course, there's always the question of "Why go through all that?" Evalin wants to kill Lhex, but why? What motivates her to
want to do these things? It will make more sense in-character if there's a good
reason for Evalin to be the bringer of death and destruction. But whatever the reason, make sure it applies to anyone and everyone, so that they are all victims and all have reason to hate and fear you.
4. "Acts of excessive and unnatural cruelty." People might make excuses for killing people in war, but what about burning down fields of crops to make innocents starve? People might understand why you'd murder someone for being in their way, but what about skinning them alive and pulling out their entrails inch by inch? Leaving their body hanging from a flagpole in the town square by their intestines so that everyone can see what you did? Once again, you need to ask, "Why is Evalin doing this?" If the answer is "Just to scare people/show how evil she is", then that's not enough. But if she has a reason, even if it's a reason that only makes sense to
her, then that makes a better story.
I don't know a lot of what motivates Evalin to do what she does, so I'll use Tock as an example. She's actually capable of doing just what I said, skinning someone, pulling out their entrails, and hanging their body out like that. But why would she do it? For knowledge. Knowledge about which parts of the body someone
needs to survive. Which ones she can remove before they die. Do people need skin? Why do we have it? If I take it away from someone, would their body adapt and survive? Etc etc.
Her reasons, to anyone
else, would be seen as the ramblings of a lunatic. But she HAS a reason, and that's needed for making the story work. Thus, if Evalin has a good reason to perform such acts, you can make the acts
extra evil by all standards of morals when you perform the acts in a way that's seen as unnecessarily cruel, excessively violent, gruesome, and so forth. If someone gets in your way, don't just murder them, but make an example of them. Use them to spread fear in the hearts of others.
That's all I can think of for now. Some of that might need some refinement, and a lot of it depends on what fits Evalin's character and personal style. Motivation is key. Which is something covered in the "Villain Workshop". It's one thing to want to kill a God and cause mass turmoil "just because you're evil". But it's another thing entirely if you do it for a reason that makes sense, in character. So to quote Tock again, she'll do
anything to build the magic city from her coma dream. If she has to one day try and destroy a whole entire city on Mizahar to make room for the one she wants to build (again, not that such a thing is likely to work in-game), she'd DO it. And she'd see it as no different from cutting down trees to make way for a new building.
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