Always entertaining to be summoned by a Paladin.
Alright, let's have a look at this one...
Bah. Mechanics are just bags of numbers. You want mechanics, you get that stupid suit of armor that lets you take hostages and siphon off their life when you're attacked. Oh, boo hoo, if we fight the villain we'll hurt the hostages, and maybe some of them are children perhaps. Yawn. The mechanics are boring.
The real fun is the roleplay-based stuff. It's where you take something like Body of the Sun, a fairly straightforward spell that causes the caster to radiate Fire damage, and turn it into Body of the Fun, a composite metamagicked arrangement that causes the victim to constantly explode with Sonic damage, demolishing everything around him and he has no idea why.
That is how you torment someone. That is Evil.
I'll take it in the opposite direction. The greatest Evil is committed when you convince Good to allow it. It's like the saying, "The only thing necessary for the triumph of Me is for Good men to do nothing." (I may be paraphrasing.)
Thus, it's not tricking Good people into committing acts of Evil - as we've already discussed, that's just turning them to Evil. No, it's convincing Good people that it would be completely acceptable for you to commit atrocities, and then doing so right in front of them. It's having them not only stand by and watch your crimes, but having them nod approvingly.
That is how you get away with it. That is how you corrupt Good. That is Evil.