Draw Step priority

[ScatmanX]

Let's say I want to do something on my opponent's Draw Step, like casting an Extirpate. I do not want him, though, to retain priority in his Draw Step, to cast the Instant I intend to Extirpate. How do I do that?

I mean, if in the end of my turn I say something like: "I have an effect on your draw step" he will be tipped off, and may play accordingly, retaining priority after he drew the card.

On the other hand, if I don't say anything,and just wait for a sign that he has passed priority, he might as well just cast a creature card or something, since he headed to his Main Phase.

I hope I have made myself clear.

[cdr]

Unfortunately, unless you're ready to deal with taking things to a judge, it's easiest to tell him ahead of time that you have an effect after he draws.

If you think it's important to not tip him off, though, you can wait until he does something that clearly indicates he's passed priority in his draw step - starting to play a land, tapping mana for a spell, or even just taking a significant pause after drawing. Be ready to take your case to a judge, though, if your opponent wants to try to go back to his draw step or wants to claim he's unilaterally moved past. If you explain to the judge that your opponent clearly indicated he was passing in his draw step, a judge who knows what he's doing will rule in your favor.

[ScatmanX]

If you think it's important to not tip him off, though, you can wait until he does something that clearly indicates he's passed priority in his draw step - starting to play a land, tapping mana for a spell, or even just taking a significant pause after drawing. Be ready to take your case to a judge, though, if your opponent wants to try to go back to his draw step.
This was what I thought... well, Thanks! =]

[DownSyndromeKarl]

You could throw him a curve if you ask him to announce all steps:

"Please announce your steps on your turn; Untap, Upkeep, Draw, Combat, ETC..."

He may think you have a combat trick and not necessarily Extirpate.

[B.C.]

I would wait for him to draw his card, then say "Still during your draw step...", at which point he will probably say something like "ok" or "yes?", indicating that he has passed priority to you, then Extirpate away.

[Shimi]

That's why when I think my opp can play some kind of effect at my draw step I just annouce that I'm drawing a card, draw it and then say "Ok?" showing that I passed priority.