I'm not sure about that.
I think it would have an extreme effect in bringing change to the readiness of the DeLucas, but by making them
ultra ready.
If another family have done this, it's entirely counter-productive if the objective was to make them cower & become unprepared.
It's only likely to have completely the opposite effect.
Cordia is gonna want blood for the attack on her unaffiliated daughter, regardless.
She's likely to want even more blood for the fact that they had the audactity to make the attack at her family's home.
After the attack, she can be in no doubt that they are at war, with someone.
Given that, the Blizzard Queen's going to up her defences & start hunting.
So, whoever it was has blown their chance & they will likely never get as good a chance again, because the DeLucas now know they are under direct threat.
"flew", not "threw".
Threw is the past tense of throw, so that sentence wouldn't make grammatical sense, anyway.
"The joke was thrown right over your head", would be grammatically correct.
Regardless, the expression is "flew over your head".