Council of Elrond

Sudden Call:

You may play this card as a resource or a hazard according to The Audience of Sauron Rules. This card may not be played as a hazard against a Wizard player, and may be included as a hazard in a Wizard's deck. You may reshuffle this card into you play deck at any time that it is in your hand (show opponent).

Can I use a method that retrieves a hazard card from my sideboard (e.g. An Unexpected Outpost, tapping & discarding a Nazgul permanent-event) to bring Sudden Call into my deck?

No. You can't use Output to access Sudden Call because it is a resource. You can play it as a hazard but it is not a hazard.

This reasoning similarly applies to Twilight -- it's a hazard, not a resource, so it can be accessed with Outpost but not Smoke Rings. This question is specifically addressed on the "newer" versions of Twilight, which state "Twilight is a hazard otherwise."