3.5; Countering Hard Counters

[Crake]

Actually, the hardest counter to illusions and shapechengers isn't the True Seeing, but the Greater Arcane Sight: you're able to literally see the magic, and automatically discerning the seen spell/effect...

Psionics-Magic Transparency

Detect Magic, Arcane Sight, and Greater Arcane Sight are useless against supernatural abilities, which is the source of most shapechangers' ability to change shape, since they only detect magic items and spells in effect.

[ShurikVch]

Detect Magic, Arcane Sight, and Greater Arcane Sight are useless against supernatural abilities, which is the source of most shapechangers' ability to change shape, since they only detect magic items and spells in effect.

[Citation needed]
On the other hand, we have this:

Can you use detect magic to detect supernatural effects?
For example, can it detect a wildshaped druid?

Supernatural abilities are magical, and thus their effects
would produce magical auras. Although the detect magic spell
doesn’t have a line entry for supernatural effect, you can use
the same line as “Magic item (caster level)”—a supernatural
effect’s caster level is equal to the creature’s Hit Dice unless
noted otherwise (Monster Manual, page 315).

[Gemini476]

The hardest counter to illusions and shapechanging is probably AMFs of various stripes, although that's obviously got a whole host of downsides. Still, though, strap some Antimagic Shackles to your resident thaumaphobic hireling and anything they walk within five feet of will find itself suddenly visible.
This will not get (Ex) shapeshifters and nonmagical illusions, of course, but those are tricky in general and I'm unsure how common the former is. Regular fake walls, mundane disguises and assorted smoke & mirrors will counter this counter.

Various divination-preventing spells like Mind Blank and the like are somewhat countered by Metafaculty, although it can't counter epic abilities.



On the subject of Shatter Mind Blank vs. Dispel Psionics: if you're facing multiple opponents with Mind Blank active, SMB is somewhat better for that specific use. It's got a larger AOE and better AOE dispel effect. However, against a single target Dispel Psionics has a massive range advantage and a targeted dispel is only slightly more expensive.
And Dispel Psionics has a whole lot more uses than SMB, of course. I imagine that SMB is probably mostly just attractive if you're a Telepath or other extremely [Mind-Affecting]-heavy manifester, but it's a very niche choice. I suppose that it's also a surprising enough choice that you'd get around those who try to specifically counter your Dispel Psionics?

[Gruftzwerg]

warlock epic feats

There are a few who can be viewed as hard counters:
(note that feat description is reduced to the important part. see link for full info)

Paragon Visionary [Epic]
Benefit:
- You can see through illusions, magical darkness, shapechangers, and other effects (as true seeing). This is a supernatural ability.

- You are automatically aware of all spells or magical effects you see. Simply by looking at a creature, you can determine if it is a divine or arcane caster, whether it has any spell-like abilities, and the highest spell or spell-like abilities it knows. This is a supernatural ability.

- When you use the voidsense invocation, you gain blindsight 60 feet.

Shadowmaster [Epic]
Benefit: You are immune to all spells with the shadow subtype and to effects that involve the use of shadows (such as the breath weapon of a shadow dragon). This is an extraordinary ability.

Souleater Incarnate [Epic]
Benefit:
- When using this feat, you consume the soul of any creature that dies within 30 feet of you. For 10 minutes following the death, you gain +10 temporary hit points and a +1 bonus on attack rolls and saving throws. Bonuses from multiple deaths stack. At the end of the 10 minutes, the soul is permanently consumed. The creature that was consumed can be raised only via a miracle, true resurrection, or wish.
- You are immune to the soulless aura and consume soul abilities of soul eaters. This is an extraordinary ability.