I have a character with 2 duplicates that is affected by a kill effect (for example, Valar).

I want to save this char and discard one of the duplicates.

This save effect is then cancelled (with To be a Kraken for example).

Am I allowed to try to save him again ?

By the rule of "One response per trigger", I wouls say no. But saves (and cancels) are not in all aspects like other responses. So I don't know.

A correlated question is:

If try to cancel an effect, but my cancel is itself cancelled, am I allowed to try to cancel the original effect again?

Comm said:

Actually, saves and cancels are exactly like other Responses. The only difference is their interrupt timing - coming between the initiation and resolution of another effect.

But remember that the "one Response per trigger" rule applies to individual copies of a card. If you have 2 separate cards with the same name, you can trigger each Response separately. (So, for example, if you have 2 characters each with Support of Harlaw, you can trigger the Response on each copy separately and stand both characters.) Since each individual dupe in your scenario is a separate Response, you could indeed use the second one after the first is canceled without violating the "one Response per trigger" rule.

Compare that to something like Davos or Viserys. If you cancel their save effects, they cannot trigger them a second time because you would be trying to use the exact same Response on the exact same card a second time. You could use a different save effect (like, say, Lightbringer), after the first was canceled, though.

Comm said:

Yes, but you need a new cancel effect. For example, suppose I play "Seductive Promise" to steal your Northern Infantry. You use Maester Vyman to cancel my event. I, in turn, use To Be a Kraken to cancel Vyman's cancel. My "Seductive Promise" is still threatening your Northern Infantry. You can't use Vyman a second time (one Response per trigger), but you could use The Hand's Judgment to take another shot at canceling my event. (Or, you could have used The Hand's Judgment on my To Be a Kraken, whichever.)

OK, thank you very much ktom. This is a lot clearer for me now.