Template and Native Outsider work well.
So, ranged attack that deals Wis drain and boosts the knight terror's Str and Wis temporarily?
That's certainly the approach I'd go for.
You know, these have a lot of potential for abuse - there's nothing in the text to suggest they can't drain the wisdom of a tribe of kobolds and gain horrendously high combat stats...
They artificially inflated Wisdom also synergies with cleric casting, which it says they favour...
Bloody hell! A spam message - don't think I've seen one on the CC boards before.
Mortis
We could limit it to twice its normal Wisdom, similar to temp hit points usually only doubling normal max hp.
Maybe even less than double Wis, if we want. Anyway, it actually seems like they can drop below normal if they don't make a successful Wis-damaging attack often enough. Want to do that?
+10 may be better, as I'm not sure we want a Wis 25 one being able to get up to Wis 50!