The Board is Set and Tale of the Great Ring

[Cw0rk]

If I discard The Tale of the Great Ring to keep my hobbit alive and my opponent plays an event, can I play The Board is Set to cancel the event and stay alive?

[TheJord]

I believe so

From the CRD
When an action (such as playing an event or using a special ability) is canceled or prevented, its effects are ignored but its costs and requirements are still paid. If that action is playing an event, that event card is discarded.

You have altered the costs of the card and it cannot be played, and is cancelled.

[Elessar's Socks]

That should work. The playing of the event itself is canceled (as opposed to just the effects), so a Shadow event has still not been played.

[TheJord]

More specifically, the cancel happens at Step 3 in "playing a card" in the CRD, where as playing happens in step 4.