Relatively new player here. I tried to search all available forums and FAQs before posting this question, but I couldn't find an answer.

I successfully quest during stage 1B 'The Hunt Begins' and trigger the Forced reaction. Among the three cards revealed is a Signs of Gollum that I chose to add to the staging area. I reveal a card to guard it, but it is a Treachery, so it leaves play immediately after its effect is applied.

My question is: Can I trigger the response on Signs of Gollum now to attach it to one of my heroes? In other words: can I use a response on a card that was not in play at the time of the trigger, but that entered play directly afterwards?

Many thanks in advance.

Following the same logic that applies to a similar situation in Wastes of Eriador, you couldn't. But in that case both effects are Forced, while in this case the second effect is a Response (I believe Forced comes before Response). Definitely a more interesting question than the one I was expecting (if the revealed encounter card recalculates the quest with its threat added, which doesn't happen).

I believe you cannot. There was a similar ruling with an enemy that had a Forced effect on it. Basically there was another effect already in play that caused you to reveal a card. Then, if the revealed card was that enemy with the same trigger the developers said that you would not trigger its effect. Unfortunately I cannot seem to find that ruling since I cannot remember which scenario it was from...

Edit: Oh yes, it was from Wastes of Eriador as the poster above me mentioned.

Here is the ruling. I made the relevant portion bold...

I think in my own games when this came up, I did not have the Warg engage. But let's see if I can talk myself out of that by looking at other similar situations.

A recent ruling tells us that Overcome by Grief attaches to a hero the first time a character leaves play, but you do not have to trigger its Forced effect at this time. The card needs to be already attached at the time the trigger is activated:

"Forced effects do not trigger unless they are in play at the time that they would trigger. This is true for Response effects as well.

Cheers,
Caleb" (source)

Based on that, the Warg would not engage.

Another similar situation: Goblin Archer does trigger off itself. He has a Forced effect that places a damage on a hero when an enemy is revealed from the encounter deck.

"Yes, the Goblin Archer will trigger its own effect after it is revealed.

Cheers,
Caleb" (source)

In this case we have another timey-wimey issue. The sequence for revealing a card goes:
1-enemy is revealed

2-enemy is added to the staging area

So the Forced effect on that Sniper... is it eligible to be triggered at point 1, or not until point 2? I guess the answer must be point 1 (otherwise it couldn't trigger of itself). So then we have a card which is in play at the time its trigger occurs (these are simultaneous I suppose, since the Archer is revealed and comes into play at the same moment). This would not have an impact on the Warg thing and we would be consistent if we did not allow the Warg to engage.

If the Forced effect is not eligible to be triggered until point 2, I don't think the current ruling on the Archer makes sense.

Anyway, long story short, I favor not having the Warg engage. It seems most like the Overcome by Grief example.

Great, thank you for your answers! This is kind of what I expected, but I wanted to make sure. What gave me some pause was the section in the FAQ that mentions that forced effects have priority over reactions. This ruling indeed clears it up very nicely:

"Forced effects do not trigger unless they are in play at the time that they would trigger. This is true for Response effects as well.

Cheers,
Caleb" (source)

Unfortunately, I often find myself in situations were the rules don't seem to be conclusive. Glad to get some help from more experienced players

On another note, I came up against following situation playing the same quest today, and also couldn't find an asnwer:

Playing two-handed, currently at stage 3B 'On the Trail', both 'players' have one hero with Signs of Gollum attached to it. After characters are committed to the quest, False Lead is revealed, causing me to shuffle one clue back into the encounter deck.

My question is: will characters controlled by the player no longer controlling a clue be removed from the quest? The way I see it, On the Trail only prevents one from committing characters to the quest, but once they are committed, they should be safe. Is this correct?

Great, thank you for your answers! This is kind of what I expected, but I wanted to make sure. What gave me some pause was the section in the FAQ that mentions that forced effects have priority over reactions. This ruling indeed clears it up very nicely:

"Forced effects do not trigger unless they are in play at the time that they would trigger. This is true for Response effects as well.

Cheers,

Caleb" (source)

Playing two-handed, currently at stage 3B 'On the Trail', both 'players' have one hero with Signs of Gollum attached to it. After characters are committed to the quest, False Lead is revealed, causing me to shuffle one clue back into the encounter deck.

My question is: will characters controlled by the player no longer controlling a clue be removed from the quest? The way I see it, On the Trail only prevents one from committing characters to the quest, but once they are committed, they should be safe. Is this correct?

You understand correctly.