So - I'm defending with Fastred against an attack, and the shadow card reads "The attacking enemy makes an additional attack after this one." After defending the attack, I trigger Fastred to reduce my threat by 2, return the enemy to the staging area. Does the additional attack still trigger?

Further question: what if the shadow card read "After this attack, the attacking enemy engages the next player and makes an immediate attack."

My assumption is that, since both triggers happen after the attack, I can choose the order in which they resolve. Which means that for the first situation, the additional attack is cancelled. But for the second one, either the engagement and immediate attack happens before I send it back to the staging area, or I send it back to the staging area, and then it engages the next player and attacks.

Am I correct in this?

In the first situation, the attack would still trigger. When you get an additonal attack as a shadow effect, the immediate resolution of that effect means you basically queue up the attack to occur, so he target player of that attack is determined at the time the effect is revealed/resolved. Even if the enemy goes to the staging area, he'll still attack you. At least, that is how I understand it and how I remember a ruling about consecutive "engage next player and attack" shadow effects on the same enemy. Let me see if I can look up that old thread.

I think in both cases the enemy attacks from staging.

Here is the thread I mentioned:

In that situation, 1 enemy got 2 shadow cards with the same effect: after this attack, enemy engages next player and attacks. The ruling was that the enemy would engage the next player and then attack that player twice. I take that to mean that the "next player" value is determined at the time that the shadow effect is resolved (which is the same moment that you reveal it), and basically 2 attacks get "queued up" as I mentioned earlier.

So in your first situation, I would have the enemy attack from the staging area.

In your second situation, even if the enemy has been bounced back to the staging area, I would have the enemy engage whoever was considered the next player at the time the shadow card was flipped over, then make an attack.

Thanks!