As I said in today’s In Today’s Magic Story, I wanted to get it out asap. As soon as the story’s up on the website, I start reading & writing. But yeah, for all y’all wondering, Jace did indeed curse, but this is the first time aloud (I think), and the first time to Vraska at any rate.
As for the compass, removing creatures from combat would help if they discovered the city, and the River Heralds are doing a good job keeping everyone from it. None of the four factions know for sure where it is. Ergo, something else is causing a constant flow of magical energy to keep it hidden. Perhaps the Immortal Sun itself is powering whatever is keeping Orazca away from prying eyes, which makes sense. Remember, it’s the Spires of Orazca, not Orazca itself, which could have an entirely different mechanic.
But yeah, the Spires are a defense, but activated only when a creature is attacking. I think it’s a Mirror of Erised situation: someone who wanted to find the macguffin, find it but not use it, would be allowed to have it. If you go attacking it blindly in a blaze of fervor, you get removed from combat. If you don’t attack, you’re presumably allowed access. Or else something triggers the rise of the city, as we see with the art of Perilous Voyage.