For more clarifications on the situation.
The player playing the sorcerer is a power-gamer. Even he admits to this. I had already given his character a ton of power by allowing him to use spell-chains (Adapted from SKR's rules), so he's already an uber-sorcerer.
He asked for the permanent protection from evil ring, and at first, I was like, "you're crazy", but I decided I would go ahead and let him have it. I forget now what I costed it at. Probably around 8-10k gp.
I have read the spell. I play a lot of clerics. I know what it does. I've just never noticed that one little line at the end of the second benefit that says "this works regardless of alignment". Because, in my mind, the spell "protection from evil" works against evil. I've never tried to exploit it, nor has it ever came up before, that the spell could be used to thwart attacks from a neutral or good enchanter, for example.
So, in the game, the sorcerer ventures down -alone- into the dark, murky depths of a flooded out dungeon section. I don't care who you are, but leaving the party behind to venture into a flooded section of dungeon is just asking to be killed.
The aboleth cast a dominate person on him from its hiding place. At the time, there were several reasons why I felt like his item would be powerless to stop this effect:
- the aboleth isn't necessarily evil. The alignment says "usually evil". I decided that, since this particular aboleth is in the middle of nowhere, with no one in particular to corrupt or enslave, it was just neutral.
- the dominate person effect of the aboleth is a psionic ability. Now, I don't know 3.0 psionics, but from my 2e days, psionics and magic just didn't mix. So, I also determined that, if the first rule didn't apply for some reason, this second one would.
So, it was about making a ruling up based on the best knowledge that I had available. I should also point out that my player also took the time to research a rule from the SRD that indicates that psionics are negating by magic effects that block magic attacks.
So, this wasn't about "changing the rules in the middle of the game", or "sticking it to my player", it was about making the best interpretation given the information that I currently had available. From that encounter, onwards, I decided that it made more sense to me that the effect should apply to creatures with the [evil] subtype, since it seems more clear, and removes all fuzziness. Otherwise, you can get into a whole alignment debate, i.e., a guy leads a good life all his life, and then kills one guy. Is he evil? Do you get a +2 against him? Bah.
And, I should point out that I literally wrote the book on magic items - Artificer's Handbook. So, I like to think that I know a *little* bit about magic items.
