Supercool Tactics Éowyn says: Setup: Reduce your threat by 3. The Overcome by Fear Objective from The Passing of the Grey Company says: Setup: attach to your threat dial. [...] Your threat cannot be reduced.

Even cooler Leadership Denethor says: Setup: Add 2 resourcws to Denethor's resource pool. Nightmare The Drúadan Forest says: Setup: [...]Add Garden of Poisons to the Staging Area. Garden of Poisons says: Heroes cannot gain resources from card effects.

What happens?

Adittionally, The Cosair Fleet from unreleased The Siege of Gondor says: Forced: At the beginning of the Staging step, place 1 resource here. Then, each player must choose: either reveal an encounter card, or assign X damage among characters he controls. X is the number of damage here.

Lets say player 1 decides to reveal an encounter card, which says: When revealed: Put 1 resource on The Corsair Fleet (we know Caleb and it's going to be there). Let's say player2decides the damage. How much damage must he assign? Equal to resources at the beginning of thestaging step or when he decides to assign the damage?

For the conflicting setup instructions, I believe the rule is that when things happen at the same time, the first player chooses the order. No doubt he'd choose the more favorable order, having Eowyn reduce threat before attaching the objective, and having Denethor gain resources before adding the Garden.

For the second situation, I believe player 2 would assign damage equal to the number of resources currently present.

Sounds reasonable.

From the Black Riders rule book:

Setup

Instructions appear on some player cards and encounter cards in The Lord of the Rings: The Black Riders. If a player card with Setup instructions is in a player’s deck at the beginning of a game, that player searches his deck for that card and follows its instructions before drawing his first hand. Similarly, if an encounter card with Setup is in the encounter deck at the beginning of a game, search the encounter deck for that card and follow its instructions before resolving the Setup instructions on the quest.