Since she came out, I assumed without much thought thsy Dany's kill effect (like the effect for other cards like Red Rain or Nighttime Raid) resolved as passives in step 4 of the framework action window on which can a challenge resolves. But ... Hammerhorn Raiders. The effect is the same: if you win a challenge (and meet a condition while doing so), X happens. But in the HR case, the effect (raising claim) must happen BEFORE claim (you can't retroactively raise claim), where something that resolved as a passive would happen after claim.
That said, when does Dany's kill effect resolve, and why? If the answer is "as a passive," then why is HR different, and when does that effect resolve?