This came up at FNM yesterday; I'm reasonably sure the judge got it wrong, but it wasn't my game and I didn't want to jump in and interfere.

Player 1 plays a Deathrite Shaman and wants to play a second one immediately afterward.
Player 2 wants to Lightning Bolt the first Shaman, then Surgical Extraction it before Player 1 can cast the second.

Who gets what they want?

The judge ruled that Player 2 wins, saying that 2 gets priority after the first Shaman enters the battlefield. This seems wrong to me.

As I understand priority, this is how it goes:

1. Player 1 casts Shaman #1 and passes priority.
2. Player 2 passes priority.
3. Shaman resolves and enters the battlefield.
4. Player 1 gains priority and casts Shaman #2.
5. Player 2 gains priority. This is the first point at which he can target Shaman #1 with Lightning Bolt, and is too late for Surgical Extraction to affect Shaman #2.

You are correct. That is a very bad judge.

I wouldn't go that far, but they did get this call incorrect. I'd suggest politely talking with them about it the next time you see them--you can point them to 116.3b, the relevant rule.

Though it's probably worth noting that if player A was attempting to use another Deathrite Shaman to cast the next spell, or was cracking a fetchland to get the land to cast it, that would make the judge's answer correct, because players can respond to either the fetchland ability or Deathrite's ability, as neither are mana abilities--they use the stack and can be responded to.

Same reason you can't shock a planeswalker after they resolve but before they use one of their abilities.

Before you go about calling someone a bad judge, especially at Regular REL, I'd suggest that you take into acount that frequently a judge at a small event like an FNM or Prerelease is the only judge there while still playing in the event. He then hears a judge call or even two simultaneous judge calls, interrupts his game and has to fix problems as quickly as possible under the risk of delaying not one but two matches (or in the case of simultaneous calls, even more). Add on top of it that players are frequently unable to present their problem in a clear fashion. Just a few weeks ago at an FNM I was called from a tense game about five minutes before time to answer some convoluted question about Thassa and Evolve and it took me a good minute and a half to finally be told that nothing's actually entering the battlefield. It's really easy to make a mistake when you're acting under that kind of pressure.

Thanks, everybody. Good to have solid confirmation.

Usually the judging is pretty good at this shop -- the guy who runs most events knows his stuff, and the local L2 plays in almost everything. But now and then they have someone else as head judge and it's not uncommon to see mistakes when that happens.