In the FAQ which is about "Archetype Stacking and Altering: What exactly counts as altering a class feature for the purpose of stacking archetypes?" said that.
In general, if a class feature grants multiple subfeatures, it’s OK to take two archetypes that only change two separate subfeatures. This includes two bard archetypes that alter or replace different bardic performances (even though bardic performance is technically a single class feature) or two fighter archetypes that replace the weapon training gained at different levels (sometimes referred to as “weapon training I, II, III, or IV”) even though those all fall under the class feature weapon training. However, if something alters the way the parent class feature works, such as a mime archetype that makes all bardic performances completely silent, with only visual components instead of auditory, you can’t take that archetype with an archetype that alters or replaces any of the sub-features. This even applies for something as small as adding 1 extra round of bardic performance each day, adding an additional bonus feat to the list of bonus feats you can select, or adding an additional class skill to the class. As always, individual GMs should feel free to houserule to allow small overlaps on a case by case basis, but the underlying rule exists due to the unpredictability of combining these changes.
And here an acquaintance says that some Magus's Archetype juet wrote "gains access to the following magus arcana" so it means that it doesn't change one subfeature. But I and some one else have different opinion. We thought that it's still change one subfeature just like the explame was wrote in this FAQ. And we still found that the designer Mark Seifter had replied that.
1) If you have a class feature that is broken into separate features with their names in italics (like bardic performance) or that are gained at multiple levels on the character chart (like weapon training), you can alter those child features separately.
2) Either way, if you mess with a parent feature (such as changing the rounds of bardic performance, or changing the ability score you use for deeds), no stacking.
3) Changing which class skills you have is messing with a parent feature. So is changing which bonus feats are on your list. If you do one of those, you can't take another archetype that also does anything with class skills or bonus feats, respectively. For instance, a fighter archetype that adds Iron Will to the list of fighter bonus feats would not stack with one that removed the 2nd level bonus feat. But the aforementioned "remove the 2nd level bonus feat" archetype would stack with one that removes the 4th level bonus feat.
But in his opinion, these things have not mention Magus Arcana so that couldn't proof that what he said is wrong.
Can somebody tell me which one make a misunderstand this FAQ?
