Scenario: If the corporation plays a sentry with a trace subroutine and the runner has a sentry icebreaker and chooses to break that subroutine, does the trace still fire?

Conversely...

If the runner does not have a sentry icebreaker, may he still bid against the trace subroutine, or does he automatically receive a tag?

Thanks in advance.

1. You broke the subroutine, the trace is part of the subroutine. I never has a chance to trigger.

2. The runner MUST bid if a trace fires, even if the bid is zero credits.

Thank you for the clarification.

If the runner does not have a sentry icebreaker, may he still bid against the trace subroutine, or does he automatically receive a tag?

The runner can try and beat the trace, but traces do not automatically give a tag when the runner fails. You do what the trace says, no more, no less.

traces are hard things to make it work for the corp. First of all if it is tied to a subroutine the Runner can simply break the subroutine that contains the trace. Second is that traces are more like a bidding war and since runners tend to be so rich in this meta they never have a difficult time to outbid the corp on trace even at 0 link. Third is the effect of most traces are not that effective. Unless it is something like midseason replacements most traces only give a single tag in which the runner could use the last click and 2 credits to clear. So for the most part if you push them past two credits higher then what the runner has then the runner will simply spend 0 and just clear the tag with 2 credits.

In the end traces take more credits from the corp than from the runner.

Try playing Sol with Surveillance Sweep.