Is there a way to counter Mindsight?

Question

Mindsight is a notoriously powerful feat from page 126 of Lords of Madness: The Book of Aberrations.

A creature that has this feat possesses innate telepathic ability that allows it to precisely pinpoint other thinking beings within range of its telepathy. The creature perceives where the others are and how powerful their intellects are.
Prerequisite: Telepathy special quality.
Benefit: A creature that has this feat can detect and pinpoint beings that are not mindless (anything with an Intelligence score of 1 or higher) within range of its telepathy. This works much like blindsense—the creature knows what square each thinking being is in, but it does not see the being, and the being still has total concealment unless the creature can see it by some other means.
The creature also perceives several observable characteristics about each being detected with mindsight, including the being’s type and Intelligence score.The creature need not take any additional or special actions to gain this information; it is as obvious to mindsight as the being’s race and clothing would be to eyesight.
Normal: Telepathy offers no special ability to sense other minds. The creature has to know that a being is there to communicate with it telepathically.

There have been discussions on this before, and it's worth discussing on RPG SE too. Is there a way for stealthy characters to hide/remain hidden from Mindsight? If so, how?

Answer 1

Just to fill in the expected argument...

The issue with mindsight is that, while it requires telepathy, and the Normal section implies that it uses telepathy, the actual benefit of the feat never says that is a form of telepathy, or that it is mind-affecting. It’s also not defined as a divination. Therefore, by the rules strictly as written, mindsight works, even if you have immunity to telepathy, to mind-affecting abilities, or to divination (e.g. you are undead or have mind blank).

This is because a feat’s requirement need not actually be related to how a feat functions (e.g. you don’t need to use Combat Expertise to benefit from Improved Trip), and the Normal section is explicitly treated as “reminder text,” to use a term from that other Wizards of the Coast product, and has no rules weight (e.g. even though the Normal section on Tower Shield Proficiency claims that nonproficiency results in taking the shield’s ACP as a penalty to all skills relating to movement, that’s not what actually happens because the “real rule,” given in the Armor section, is that all Strength- and Dexterity-based skill and ability checks take the penalty). Thus, there simply is no rule that mindsight is or relies on telepathy.

In practice, in all but the strictest games, this oversight it ignored, and lots of things protect against mindsight, such as immunity to telepathy, mind-affecting abilities, or divinations. Many also extend the Darkstalker feat to cover mindsight (and the lifesight feat from Libris Mortis). As Sandwich pointed out in a previous version of his answer, the Madness ability of allips would also form a serious deterrent to the mindseer when Mindsight is treated as telepathy, as the mindseer would quickly lose all Wisdom.

Strict-RAW defenses

Even under the rules read as strictly as possible, there are still some defenses against Mindsight.

Mindlessness

Mindless creatures are immune to Mindsight. Not terribly helpful for players since you can’t play a mindless creature, but it’s worth keeping in mind, particularly as a DM. Note that intelligent creatures that are usually immune to mind-affecting things, like intelligent undead, are not immune under this super-strict RAW.

Hellbreaker

If the mindseer is put inside a hellbreaker’s Telepathic Static, as Matthieu M. discovered, it loses telepathy, and can no longer use the Mindsight feat as it has lost the requirement.

Tower Shields

As Forrestfire just pointed out to me, when you have Total Cover (as when employing a tower shield), creatures cannot draw line of effect to you. Normally, this doesn’t matter much since touch attacks and targeted spells still work against the tower-shield user, but Mindsight is not targeted, so the shield somehow blocks the Mindsight, despite being far thinner than the requisite blocking material. This is really just an abuse of the terrible wording on that use of the tower shield, more than anything else.

Cerebral Blind

As Sandwich found, the Cerebral Blind class feature of the slayer class can be read as blocking all effects that reveal location. Note that the wording is somewhat ambiguous.

Answer 2

I just accidentally ran into the HellBreaker class after reading this question. At level 1, this prestige class grants:

Telepathic Static (Su): Beginning at 1st level, you emit a field of psychic chatter out to a range of 20 feet, negating the telepathy ability of all creatures within range. [...]

This seems like a counter to Mindsight, and there might be other ways to negate telepathy.

Answer 3

Cerebral Blind

From the slayer Prestige class:

Cerebral Blind (Su): After reaching 6th level, a slayer is protected from all devices, powers, and spells that reveal location. This ability protects against information gathering by clairsentience powers or effects that reveal location.

The ability even foils bend reality, limited wish, miracle, reality revision, and wish when they are used to gain information about the slayer’s location (however, metafaculty can pierce this protective barrier). In the case of remote viewing or scrying that scans an area a slayer is in, the effect works, but the slayer simply isn’t detected. Remote viewing or scrying attempts that are targeted specifically at a slayer do not work. This ability is active as long as the slayer is psionically focused.

Cloud Mind

Cloud Mind, From the Psion spell list:

You make yourself completely undetectable to the subject by erasing all awareness of your presence from its mind. This power has the following effects.

First, you are invisible and inaudible to the creature. It cannot even detect your presence by means of blindsense, blindsight, scent, or tremorsense. It cannot pinpoint your location by any means.

Second, the subject remains unaware of your actions, provided you do not make any attacks or cause any obvious or directly threatening changes in the subject’s environment. If you attack the subject creature, the effect ends.

If you take an action that creates a sustained and obvious change in the subject’s environment—for example, attacking a creature aside from the subject or moving a large or attended object the subject can see—the subject immediately gains a new saving throw against the power. An ally of the subject creature that is able to see or perceive you can use a move action to warn the subject and thereby grant it a new saving throw.