So everyone is aware, the 'flags as evil' provided by the 3.5 version is not a single "yes/no" value, but a gradient that does care about the nature of the thing.
This is in interesting counterpoint to what I have found in the 2e version which *is* a strict "Is/is-not evil", but accomanied by the rather complicated "Evil intent" parameter.
As such, I figured I'd post the 3.5 aura strength table here for ease of reference for everyone. Note that it's the same for all 4 Detect Alignment variants, just trade out [Evil] for the alignment of choice, and probably ignore the "undead" row.
A few notes:Aura Power
An evil aura’s power depends on the type of evil creature or object that you’re detecting and its HD, caster level, or (in the case of a cleric) class level; see the accompanying table. If an aura falls into more than one strength category, the spell indicates the stronger of the two.
*Except for undead and outsiders, which have their own entries on the table.
Creature/Object Faint Aura Moderate Aura Strong Aura OverwhelmingAura Evil Creature* (HD) 10 or lower 11-25 26-50 51+ Undead (HD) 2 or lower 3-8 9-20 21+ Evil Outsider (HD) 1 or lower 2-4 5-10 11+ Cleric of an Evil Deity** (Class Levels) 1 2-4 5-10 11+ Evil item or spell (CL) 2 or lower 3-8 9-20 21+
**Some characters who are not clerics may radiate an aura of equivalent power. The class description will indicate whether this applies.
https://www.d20srd.org/srd/spells/detectEvil.htm
- Classes like Blackguard are those explicitly listed as having an aura of Evil similar to clerics. Paladins have an aura of Good similar to clerics, as well. Why neither has an Aura of Law or Chaos is beyond my knowledge.
- A neutral cleric of an evil god detects as evil appropriate for their class levels.
- I usually have seen that full class level is considered, even if only 1 of them is cleric. The alternative reading is "Only your cleric class levels", but that interacts very weirdly with PRCs that are effectively extensions of cleric (and your Cleric/Hierophant/Solar Channeler is counted as way lower than they have any right to be), particularly considering that cleric by itself is only useful past the first level for PRC unlocks.
- The "Evil magic item or spell" listing is a bit vague, since it's unclear if it means spell level or caster level, and by strict interpretation, a level 30 casting [Darkbolt] (Cleric/Wizard 2) would flag as "Overwhelming Evil". or it could be "Faint" if it was supposed to check Spell level.
- An epic-level Good-aligned cleric carrying a Lich's phylactery (or more likely an Requires:Evil epic item) would detect as both Overwhelmingly Good, and Overwhelmingly Evil. Just because they detect as Evil doesn't mean Smite will work, nor is indicative of actual alignment.
- I would personally be a proponent to reduce the lower-HD of "Evil Creatures" off the chart, so it progresses [11-15/16-25/26-50/50+], or a similar effect. A moderate level fighter would (depending on #4) show up as a lower evil than a neutral cleric with an active Death-Knell buff.
- To actually identify that a given person is emitting a given alignment requires the caster to sit there for 18 seconds studiously looking over the target. If you choose to move away first because a creep decided to peer at you across the campfire that is fair play, as is popping a potion of Nondetection and decrying them for suppressing your halfling culture. Otherwise they just get either (a) *any* of the listed triggers exist in the area scanned (Which could literally be a CL1 Requires:Evil item), or (b) what the biggest aura is. In neither case does it tie it to a person or thing
- Nondetection is Sorc/Wis 3. The potion cost would be 750GP by default, but making it short duration and cheaper could allow for a reactionary counter, as potions take much less than 18 seconds to use. As do scrolls, for that matter. It's still an opposed CL check though, so UMD might not be reliable.