I am not thrilled about doing this as I suspect I’m kicking a hornet’s nest, but I am looking for an official ruling as to whether a summoner (unchained) with an evil subtype eidolon is allowable in PFS. (e.g. a lawful neutral summoner with a devil subtype eidolon). I request a ruling for two reasons: (1) I do not want to have to rebuild my character later due to rule misinterpretation and (2) LWD Technologies Inc. (makers of Hero Lab) stated a formal ruling was needed before they will eliminate the error messages that come up when creating such a character with their software.
The conflict arises from two sections of the rules. First, page 9 of the Guide to Pathfinder Society Organized Play it states that "No evil alignments are allowed in Pathfinder Society Organized Play." The second come from page 25 of Pathfinder Unchained which states “An eidolon must be within one alignment step of the summoner who calls it (so a neutral good summoner can call a neutral, lawful good, or chaotic good eidolon) . . . .” This was not an issue for summoners until the unchained summoner was mandated as the original class required the eidolon’s alignment match the summoner’s (APG p 55).
My interpretation of this issue would allow such characters based on the following presidents and arguments. First off, there are plenty of “evil” things allowed in PFS that do not breakdown the game although they do get debated frequently. Spells with an evil descriptor are allowed without impacting alignment (although the use of any spell in an evil manner could be an issue, as I understand it). Summoning demons and devils to do one’s bidding is a valid tactic (e.g. see Summon Monster lists, etc.). Neutral clerics who worship evil gods are playable as are diabolists (who are lawful neutral). Bloodlines which are reflective of traditionally evil subtypes are allowed (e.g. Infernal and Abyssal bloodlines for sorcerers and bloodragers). In light of this, playing a neutral summoner with an eidolon with of an evil subtype should be not any more of a problem than the examples above.
Banning evil subtypes eliminates a third of the available eidolon options. While it is impossible for anyone to read the mind for the intent of the game designers, similarity of wording between the rules for summoner/eidolon alignment and cleric/deity alignment make me suspect that no ban was intended.
In searching the forums, I have found most of the aforementioned examples have been a source of debate, mainly stemming from their potential interaction with the “no evil alignments” rule and fear that the game will be made unfriendly. I doubt this sort of arguing will ever be settled. The most damning counterargument I could find to a summoner with an evil subtype eidolon was concern about encountering players who play their eidolons as their characters and that this would allow an evil character to sneak in. In response to this I would say the problem stems from the actions of the player (see “don’t be a jerk”) and not the label of “evil”. In the end, ensuring characters are made in such a way that they can “explore, report and cooperate” with other characters, regardless of alignment, seems to be the best route to ensure everyone can have fun at the table.