Now, someone can correct me on this since I’m still getting a handle on how “the stack” works.

If your opponent declared a blocker to your attack, and then flashed a card onto the field, that is taken priority.

You declare attack -> they respond by declared a flash blocker -> attack/blockers resolve since you declared attack

If you decide to play a card in response to their blocker, I would assume the attack resolves first because that’s how the stack is playing out. When you play your card in response to their blocker, you are already attacking, that takes priority. So I would assume the attack would go first, then your card would play on the fallout of that attack phase.

Again, I’m still newish to how stacks play out, it can be tricky at times to figure out the stack.