HIghest non-magical AC

[Sholos]

In a recent encounter, my party ran across some very hard nuts to crack. Their AC was around 30 each, which we figured meant they had some very sweet armor we could loot after the battle. Cut to the fight being over and we scan for magic. Apparently nothing on them was magical at all. So I'm left wondering, how in the world do level 12 humans get an AC of 30 without magical assistance? Is that actually possible?

[Pilo]

Maybe they were psionic?

However : 10+1 (Dex) +8 (Full plate) + 4 (Tower shield) + 1 (luck of the heroes) + 1 (Dodge) + 12 (superior expertise) = 37.

[Deox]

Sounds reasonable, though some sort of temporary magic may have been in play.

10 (base) + 5 (breastplate) + 3 (dex) + 2 (shield, non tower) = 20.

Phalanx Fighting feat adds +1 armor bonus and an additional +2 if forming a shield wall.
Shieldmate and Improved Shieldmate provide another +2.
Combat Expertise could be in play, let's assume a +5 bonus (-5 to attack).

20 (from above) + 3 (Phalanx Fighting + Shield wall) + 2 (Imp. Shieldmate) + 5 (Combat Expertise) = 31 AC.

If we add temporary magic items (potion of barkskin +2, oil of magic vestment +2 (two - one for armor and one for shield) that gives us another +6 for a total of 37.

[Biffoniacus_Furiou]

Nothing on them was magical at all, but they may have been buffed: Inertial Armor (http://www.d20srd.org/srd/psionic/powers/inertialArmor.htm) + Force Screen (http://www.d20srd.org/srd/psionic/powers/forceScreen.htm) + Thicken Skin (http://www.d20srd.org/srd/psionic/powers/thickenSkin.htm) + Defensive Precognition (http://www.d20srd.org/srd/psionic/powers/precognitionDefensive.htm) + Animal Affinity (http://www.d20srd.org/srd/psionic/powers/animalAffinity.htm) (Dex).

If they're 5th level and augment each of those and have Dex 16 (or Dex 14 and Psionic Dodge (http://www.d20srd.org/srd/psionic/psionicFeats.htm#psionicDodge), or Dex 10 and Expeditious Dodge + Psionic Dodge) then that's an AC of 30. Plus if your group isn't using magic/psionics transparency then detect magic wouldn't notice any of that.

[Max Caysey]

In a recent encounter, my party ran across some very hard nuts to crack. Their AC was around 30 each, which we figured meant they had some very sweet armor we could loot after the battle. Cut to the fight being over and we scan for magic. Apparently nothing on them was magical at all. So I'm left wondering, how in the world do level 12 humans get an AC of 30 without magical assistance? Is that actually possible?

Well

10+3 dex, +9 mithral battleplate +4 towershield +1 shield specialization + 2 for heavy armor optimization and improved heavy armor optimization +1 dodge. Thats 30 without combat expertise. Could also have the fist of the forest con bonus to ac, and the deepwarden con instead of dex to ac. Could also be dwarven defender for added dodge. Could be fighting on the defensive too...

[ben-zayb]

Superior Expertise turns AC up to 22, fighting defensively for up to 24, full plate and tower shield for up to 36.

[ShurikVch]

Cancer Mage
Vile Rigidity
Arbitrary high AC

[Necroticplague]

Define 'magic'.

Battledancer1/monk1/sorceror 3(take Ascetic Mage)/ghost4. Cha to AC 3 times (twice as an untyped bonus, once as deflection), and +4 to CHA. Assuming a starting 18 in cha and 16 in DEX (because it's not like you need STR or CON), that provides a solid AC of 31 without any buffs at all. A stat-boosting spell to either Cha or Dex could ratchet that up higher. And thus build still has room for more levels. Plus, only one of the bonuses is typed, so there's plenty of room for direct bonuses to AC (though, as an incoporeal creature, it can't benefit from natural armor).

[Rebel7284]

There are several ways to add a stat to AC.
http://www.giantitp.com/forums/showthread.php?125732-3-x-X-stat-to-Y-bonus

Something as simple as Swordsage 2/factotum 3 can have 10 + 4 dex + 4 wis + 4 int + 4 chain shirt = 26.

However, you are talking about level 12! AC can be way higher at that point.

edit: I usually do this build with Dragonborn Mongrelfolk, but human works too:

Arctic (dragon 306, P61) Human Strongarm Ranger 3/Stoneblessed 3/Fist of the Forest 1/Deepwarden 1/Monk 1/Dwarf Paragon 3

Con 27 when naked: 18 base +2 Arctic +2 Stoneblessed +2 Dwarf Paragon +3 level
Wis 18

30 AC totally naked.

[Telonius]

What were they wearing - any armor at all? I suppose they could be Monks or Swordsages with arbitrarily high Wisdom. Fist of the Forest could add Con to AC. Levels in Duelist, Int to AC. The Photosynthetic Skin (http://www.d20srd.org/srd/variant/buildingCharacters/spelltouchedFeats.htm) feat would give you +2 Natural Armor.

[Zaq]

It's possible that they had buffs cast on themselves, rather than actual magical armor. (Buffs go away when you die, right? Your corpse doesn't ping as magical?) Barkskin, for example, is a decent natural armor buff, and hell, it almost certainly goes away when you die, since it specifies "living creature touched" as its target.

Or another thought presents itself . . . Most GMs don't like sending Exalted Good enemies up against the party willy-nilly, but I could see a tweaked Vow of Poverty being used as a way for the GM to slap numbers onto enemies without loading them up with tons of loot. VoP gives a few different flavors of bonuses to AC, and when combined with decent stats and maybe a way to get more than one stat to AC (Monk for WIS, Deepwarden for CON, etc.), you could end up with a respectable total.

I know there's also ways of making fighting defensively and/or using Combat Expertise more effective than usual. Someone (true shinken, I think?) had a handbook on it a while back, though I'm not sure if it would be easy to find that handbook now. I'm not sure exactly how big a bonus you can get from it, but it might be a piece of a larger puzzle.

Also, they might have had some kind of miss chance, so it just seemed like they had high AC. Most of the good ways of getting miss chance are magical, of course, but I'm sure there's at least a couple that might work.

[Greenish]

Not too hard. (http://www.giantitp.com/forums/showthread.php?178445-A-short-guide-to-defensive-fighting)

[Necroticplague]

Also, it could be that the magic in their items was covered up with a Magic Aura spell.

[Der_DWSage]

Yeah, it honestly wouldn't be too difficult to get AC into the 30s if they're focusing on it.

Base 10 + 16 Dexterity + Tower Shield + Mithril Full Plate + Combat Expertise gets them to 30 on the nose, and that's pretty low-optimization right there.

[kardar233]

Thaalud Stone Armour is the highest AC non-magical armour at +12, but it's rather rare, comes from a rare adventure rather than a sourcebook (Anauroch: The Empire of Shade) and it consists of giant plates of stone so I think you would have noticed it. Unlikely to be it.