Perhaps Naagloshii have limited collective memory as a form of Intellectus, and one of the inmates originally saw the runes. We are getting more limited forms of Intellectus, in Battle Ground alone we got the Knights Banner, and the Valkyries catalogue, so a collective memory of harmful things would be useful. All Naagloshii would therefore be forewarned of what one of their kind found harmful, like following Donald Morgan out of the Never Never into an apparently innocuous desert. Naagloshii learn not only from their mistakes, they learn from all the mistakes everyone of their kind make. That would make them badass, it also means you can never repeat the same trick on any Naagloshii, like you could with a different Blamp, or Fae. Morgan’s trick could not be repeated on any Naagloshii.
Obviously half human scions don’t have this, and this may be a blind spot, an absence in their power set which makes them vulnerable, otherwise Goodman Grey wouldn’t have been hired a second time by Harry Dresden.
