Defense against Iaijutsu Stike (OA)...

[Mallus]

...is there one? Other than winning initiative?

Uncanny Dodge prevents the denial of dex, but does that have any bearing on Iaijutsu Strike? Even with UD a target is stil flat-footed...

 

[green slime]

Yep. Don't stand so close to potential enemies! It's dangerous!

 

[Hypersmurf]

Foresight.

-Hyp.

 

[Mallus]

A 9th level spell??!!

Ok, so there's no defense against Iaijutsu Strike. Got it.

Except acting before the striker, or not being in range. OK...

 

[Hypersmurf]

A 9th level spell??!!

Hey, it does exactly what you asked for, doesn't it?

-Hyp.

 

[Crothian]

fortification might, I dion't recall the specific limitations of Iaijutsu Stike

 

[Ankh-Morpork Guard]

A 9th level spell??!!

Ok, so there's no defense against Iaijutsu Strike. Got it.

Except acting before the striker, or not being in range. OK...

What about a good AC?

 

[Plane Sailing]

Concealment. Got to love those miss chances!

Cloak of displacement, Blink, Blur, obscuring mist or even standing in a bush if you want the low-magic equivalent!

 

[Darkness]

A 9th level spell??!!

Use a lower-level spell then.

Mirror image, for example. Some other illusions are good too.

 

[Saeviomagy]

Oooh, Oooh! I've got one!

Not letting iaijutsu strike in the game because it's stupid. I think that's a pretty good counter...