First up for today, it’s an answer to Tony, who noted that “The Practical Enchanter says that curses can be cast by people who do not have magical abilities, yet then it goes on to categorize curses as spells with levels. If curses are spells and commoners have no spellcasting ability, how’s that work?”
Well, that’s easy enough: almost uniquely, the spell level modifiers on a curse can reduce it’s level below zero – and there are no requirements for casting such “spells”. For example, if an ordinary person – possibly after being aided by someone who kept them from dying or having a lingering death for dramatic purposes – is cursing a child of theirs (-2) who personally inflicted a mortal wound on them (-2), and is willing to suffer severe backlash (-2), and fuels the curse with (1d4 x 500 XP) (-1), they wind up with a net modifier of -7 spell levels. If they attempt a curse with a base level of 6 or less, they’ll wind up with a net spell level of (-1) – which anyone can manage.
Of course, that’s an extreme example, and a rarity even under such circumstances. Most people don’t have the focused malice, the concentration, or the inclination to lay good curses – although this does provide a reason to avoid pointlessly slaughtering the peasantry. Even minor curses can be annoying.
Still, if the foul Prince Karnacht stabs his father King Lerill with a poisoned blade and leaves him to die (a prelude to blaming a neighboring kingdom for his death and declaring war upon it while simultaneously seizing the throne), he should not be surprised to find that his father, while only an eighth-level noble with no spellcasting ability, has cursed him with his dying breath and words written in his own blood “to be brought down by the children of his deeds”. As a sixth-level curse this Affliction can use a “Suggestion” effect six or seven times per day – which it will use against the King and his commanders to try and allow the occasional vengeful child to escape the upcoming massacres. When a few such children grow up and become adventurer’s (thanks to more subtle Suggestions), King Karnacht may well meet his doom at their hands. After all, the avengers will be mysteriously “lucky” enough to have an suggestible old servant absent-mindedly reveal the location of the secret passage to his chambers…
Now that’s a pretty classical plot, but now you actually have some reason for it; King Karnacht often failed to follow the rules of the Evil Overlord List because he was being magically manipulated. His officers mysteriously took pity on the occasional child, or committed obvious blunders, for the same reason. Why did the kids come together? Why did they become adventurers? Why did they stay determined to seek revenge? Why were they the only ones to stumble on the secret passage? Because the curse is fulfilling it’s wording. There may be more efficient ways to get things done, but this is a curse, not an engineer on assignment.
In classical terms, the existence of such curses equates to the purported ability of dying people to curse their murderers with terrible fates and with the supposed ability of parents to lay curses and blessings on their offspring – a notion goes back as far as we have records, and can be found in sources ranging from Sumeria to pre-dynastic China and the old testament.
In d20 terms, spells with negative spell levels are only possible if they’re either bits of folk magic with no actual game effect – such as kitchen charms to keep cakes from falling, cellar charms to help keep the bugs out of the stored vegetables, cleansing charms, and a thousand other tiny items – or if all the real work is carried out by someone else. Thus you have the occasional efficacy of perfectly ordinary people offering prayers to gods or cursing their tormentors. There are things out there that listen – sometimes even to people who don’t have the magic to reach them directly and reliably.