Archive Trap and sac lands

[Mr. Fantastic]

I sacrificed a Scalding Tarn during my opponent's end step and he "responded" with Archive Trap using it's alternative casting condition.  I wanted to search for a Mountain but he insisted that the Trap milled me first, as I was searching and before the mountain hit play.  As I understand the rules, you can't play Trap until your opponent actually searches his or her deck but he said that "you can mill them before the Mountain actually comes into play."

I disagreed.  Am I wrong?

[Yare]

Archive Trap's alternate cost can only be used after the search has actually been performed. Before then, he'll have to hardcast it. So, you'll get to search for your land before he gets to Archive Trap you.

[Mr. Fantastic]

Thank you for the quick response, as always.  I was actually second guessing myself for a second there.  

Of course my opponent instantly quit me when I wouldn't let him cheat but that's a story for another thread...

Yes, this is a story for another thread, so there's no point to even be mentioning it here.  In the future, please don't.

-- Clariax