AP: “Go”.

NAP wants to tap his own Arachnus Spinner, search for Arachnus Web, put it on opponent 4+ power creature.

He wants to do that during the end step, so that Arachnus Web will be destroyed at the end of NAP turn.

Under current IPG, what is the best way to accomplish this? What should NAP say/do?

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in postcombat main phase?

Best way: “End step, activate Spinner targeting your guy.”

If NAP doesn't specify: No, I would not rule that NAP has acted in Main Phase 2.

Originally posted by MTR:

If the active player passes priority during their second main phase, or uses a phrase such as “Go” or “Your Turn” at any time, the non-active player is assumed to be acting in the end of turn step unless they are affecting how or whether an end of turn ability triggers. End of turn triggered abilities that do not target resolve after the non-active player passes priority.

According to MTR 4.2, if the AP says “Go,” the NAP, should they respond, is
assumed to be acting in the End of Turn Step unless they are affecting how
or whether an EOT trigger happens. So, the NAP's response is going to be
in the end step unless something unusual occurs or they state specifically
that it's in the main phase. Of course, they could always just say “During
your end step” or something similar to achieve the same effect, the
advantage of which is clarity.

Originally posted by Francesco Scialpi:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in postcombat main phase?

Excuse me, what I really meant to say was:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in end step, but before arachnus web ability trigger?

Originally posted by Francesco Scialpi:

Originally posted by Francesco Scialpi:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in postcombat main phase?

Excuse me, what I really meant to say was:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in end step, but before arachnus web ability trigger?

I don't understand. There is no Arachnus Web ability yet, right? NAP is only fetching it now, in AP's End Step? Is there a second Arachnus Web?

There is no way NAP can act in the end step and still have Arachnus Web
trigger during that end step. Arachnus Web always triggers at the
beginning of the end step, so it will wait for the next opportunity to
trigger if it is not on the battlefield when the end step begins.

Originally posted by Dan Collins:

Originally posted by Francesco Scialpi:

Originally posted by Francesco Scialpi:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in postcombat main phase?

Excuse me, what I really meant to say was:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in end step, but before arachnus web ability trigger?

I don't understand. There is no Arachnus Web ability yet, right? NAP is only fetching it now, in AP's End Step? Is there a second Arachnus Web?

AP: “combat”
NAP does some stuff (e.g. “tap this creature”)

After that, BoC abilities trigger.

Similarly, one might argue:

AP: “Go”.
NAP taps Arachnus Spinner etc. etc.

After that, Beginning of End Step abilities trigger.

Is this wrong? Am I missing some difference?

Originally posted by Francesco Scialpi:

Originally posted by Dan Collins:

Originally posted by Francesco Scialpi:

Originally posted by Francesco Scialpi:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in postcombat main phase?

Excuse me, what I really meant to say was:

If NAP acts after AP has said “Go”, without saying anything, should we rule that he has acted in end step, but before arachnus web ability trigger?

I don't understand. There is no Arachnus Web ability yet, right? NAP is only fetching it now, in AP's End Step? Is there a second Arachnus Web?

AP: “combat”
NAP does some stuff (e.g. “tap this creature”)

After that, BoC abilities trigger.

Similarly, one might argue:

AP: “Go”.
NAP taps Arachnus Spinner etc. etc.

After that, Beginning of End Step abilities trigger.

Is this wrong? Am I missing some difference?

Yes? The End Step ability doesn't trigger because the Web wasn't in play at the beginning of the End Step. That's why NAP is acting in the End Step instead of Main 2. BoC abilities still trigger at the beginning of the step, but the shortcut allows them to be announced a little bit later. The text I quoted in my first reply doesn't say anything like that for EoT abilities.

I think the distinction is that the Arachnus Web is not on the battlefield
at the time it would trigger. Certainly yes, if a Web is already on the
battlefield, NAP is allowed to do things during the End Step before the
Arachnus Web's trigger resolves. However, if the Web is not on the
battlefield when it's ability would trigger, then it won't trigger until
the next opportunity. Similarly, if NAP somehow (and for some reason) cast
a Citadel Siege specifically during beginning of combat, it would not
trigger that turn, as the time for its trigger has passed.