Hidden Master and its interpretations.

[wolfen]

As prd:
At 20th level, a ninja becomes a true master of her art. She can, as a standard action, cast greater invisibility on herself. While invisible in this way, she cannot be detected by any means, and not even invisibility purge, see invisibility, and true seeing can reveal her. She uses her ninja level as her caster level for this ability. Using this ability consumes 3 ki points from her ki pool."

As I read this I notice a few things it seems most people do not consider. It specifically states that it is the same as a greater invisibility spell which states that it does not effect sound or smell. Following with while invisible in this way, as in greater invisibility, she cannot be detected in any way. Which it states invisibility purge, see invisibility, and true seeing do not effect this. All of these have nothing to do with sound or smell only sight.

From this I feel that most people are misconstruing the "By any means" portion of the text to mean all forms of detection and not just those that would normally effect invisibility. I know most say its a cap stone and that invisibility is normally easy to beat via scent, blind sight, etc. but each of these also has something that easily overcomes them aswell. I am not looking for a flame fest over wether or not this ability is broken or not just what others think of my thoughts.

So I am curious on what others think of my deduction and if I left out anything.

[Troubleshooter]

People who want to read into it, will read more stuff into it.

Should a 20th level ninja's ability keep her protected even against a new 6th level Divination spell that's released in the next Ultimate book? Yes.

Are there going to be rules lawyers who point at the line that says 'cannot be detected by any means' and try to argue that she also cannot be heard while screaming and cannot be felt while attacking? Yes. That is part of the community that follows this game.

Like freedom of movement, you should take a reasonable approach and not read TOO much into what the ability will allow. But I will add that I don't think it's out of the question for a 20th level ninja to be able to sneak within 30 feet of a CR 1/2 dog without being instantly noticed.

[Master_Crafter]

I would agree that Hidden master is primarily a sight-based ability and that abilities such as scent might pierce it, as there is no real way of covering this up in PF save for a massive stench that would have to affect an area.

As for blind sight, I think that since this ability primarily detects upon sound it would also have a chance to pierce this ability. However, since a ninja likely does practice moving silently as well, I would still require a perception Vs stealth in this case, probably allowing the ninja to utilize the +20 stealth modifier, but also giving the creature with blind sight a +20 to their perception to offset.

Of course, all of this is technically house rules given the subsequent wording you've pointed out. But it at least seems to be a reasonable interpretation and is how I would probably run it at my table.

[Troubleshooter]

As a further note, while Blindsight in theory can be easily beaten, it's not in practice. The description puts it as some super-advanced form of a normal sense, or combination of senses such as echolocation. But creatures don't actually have specific forms of Blindsight, such as one that can see heat, another with extreme hearing, or another with vibration of the air -- those remain only very rare exceptions, such as the Destrachan. If they did, then they could be circumvented by things such as silence spells. But the only specificity beyond that is that it does not work in a vacuum. How do you hide from a Clouded Vision oracle? Break line of sight. That's about the only way.