What I'm doing is twofold. One: 'evil' is defined as 'that which is philosophically opposed to me'. 'People trying to kill me' works well enough. This is the definition I use for detect evil and protection from evil.
Two: 'evil' and 'good' is defined as servants of entropic or regular immortals. An evil cleric of Thanatos might cast 'unholy blight' on a group of adventurers. Those adventurers unaligned to any particular immortal would take half damage. Those adventurers aligned to a regular immortal (say, a cleric of Ixion, or a paladin) would take full damage. Those adventurers aligned to an entropic immortal (say, an avenger/blackguard or another cleric of Thanatos) take no damage. 'holy smite' is the opposite. As they have different effects, I have retained all the variants of holy smite/unholy blight.
For the purpose of this, I treat anyone who is seriously devoted to an Immortal or a philosophy, regardless of whether they get power from it, to count as affected by aligned spells. Say, an orcish berserker fully devoted to the cause of destruction will be fully affected by holy smite.
This variant does make protection from evil more powerful, as it will work in virtually every battle, rather than just those against evil creatures. For this reason, GMs may want to weaken it. However, it should remain useless against creatures with no hostile intent, such as constructs. I would count the inherent maliciousness in mindless undead such as skeletons as 'evil' for the purposes of the spell, however.
As a house rule, I require skill rolls for various magical effects. Detect evil requires a sense motive check (fortunately in 3.5, paladins get this as a class feature). This is opposed by a bluff check, so blackguards seeking to remain hidden stack up on that skill. Detect evil CAN detect evil in the second meaning: clerics of Thanatos detect clerics of Ixion, and vice versa. But this is heavily affected by the sense motive roll, which becomes easier as the opponent is more obvious or not. A scheming cleric of Thanatos in the middle of the king's court, who is not actively seeking to depose of the good cleric, will be harder to detect than an avenger in full dark armour charging towards the paladin. The bluff roll, naturally, requires the character to be making some attempt to hide their aura... the avenger in full battle mode gets no such roll.
In addition, the range of detect spells in general varies according to the aura strength involved. A moderate aura is detectable at the usual 60'; an overwhelming aura may be detectable miles away, depending on the circumstances.
Hm. I think that's about that.
Detect evil existed, detect good did not. Both worked against hostility rather than cosmic good or evil.
How about one spell then - Detect Enemy ;)
Two: 'evil' and 'good' is defined as servants of entropic or regular immortals.
I assume that you're not using the Immortals alignment for this. What you could use is the Immortal's list of allies and enemies (eg an Entropic Immortal's enemies may not just be from the other 4 Spheres but may be from the Sphere of Entropy - Likewise an Immortal from the Sphere of Matter may have enemies in any of the 5 Spheres not just Entropy) to decide who detects as 'good' or 'evil'.
However that said you do have some good ideas.
Regards,
Gary
How about one spell then - Detect Enemy ;)
Yup, that's effectively what Detect Evil becomes.
I assume that you're not using the Immortals alignment for this. What you could use is the Immortal's list of allies and enemies (eg an Entropic Immortal's enemies may not just be from the other 4 Spheres but may be from the Sphere of Entropy - Likewise an Immortal from the Sphere of Matter may have enemies in any of the 5 Spheres not just Entropy) to decide who detects as 'good' or 'evil'.
However that said you do have some good ideas.
Regards,
Gary
Yup, I'm making the particular Immortal worshipped secondary to whether they're Entropic or not. The effects are generated by the source of the power, rather than the Immortal itself. In my campaign, I'm trying hard to make Immortals different to gods, and one of those ways is de-emphasising one's personal relationship with a particular Immortal (and re-emphasising one's relationship to the pantheon of a particular church, in this case the churches of Karameikos and Traladara). For one, even Clerics can easily move between Immortals of the same pantheon, and most of their domain choices will come from the pantheon rather than their patron Immortal (Traladara priests IMC have circuits they travel around, as not all towns or villages have priests, and thus the Travel domain is available to all priests of the Church of Traladara, regardless of their patron Immortal).
That said, odd effects appear all over the place. IMC, there are a couple of entropic Immortals in the Karameikan pantheon (though none in the Traladaran). Clerics of Karameikos nevertheless use holy smite and are affected by unholy blight, even if an entropic Immortal is their favoured Immortal... because more importantly than their particular Immortal, they follow the philosophies of the church. Only if they abandon the precepts of the church (or twist them) and follow the teachings of that Immortal above that of the church do they use unholy blight and become affected by holy smite.
Any individual GM may want to re-emphasise the particular Immortal worshipped, and use their list of allies and enemies, that's perfectly valid.
I just like it the way I do it; feels more 'real' to me, from what I know of ancient pantheons.