I thought it would good to share this Q&A I had with Caleb… Something seems curious about it to me.

I'd been wondering about playing Erebor Guard off the top of the deck using Gandalf's ability: can you trigger the EG's Response? How exactly does it play out? Explicitly, I asked:

'Can you trigger the Erebor Guard's Response (lowering his cost) if you're playing him off the top of your deck with hero Gandalf? The possible issue is that, even if considered part of your hand, the Erebor Guard is still the top card of the deck, so does triggering his Response discard himself but still work? Does it discard the two cards below him? Can you not trigger it at all? If you CAN trigger it, when do you decide on whether you even want to trigger the Response? Gandalf's passive ability "instantly" turns the top card of your deck faceup, so perhaps I would use that information to decide whether I want to use the Response or not, if the timing allowed for that.'

The answer:

Quote

Gandalf’s ability lets you play the top card of your deck “as if it was in your hand.” When you play a card from your hand, you place it in front of you and pay its cost before resolving the card. For the instant it takes you to play a card, it is not in your hand or in play - it is being played.

So, when you play Erebor Guard, you place it in front of you, pay its cost, and resolve playing the card. Therefore, it is not the top card of your deck when you play it and it cannot be discarded by its own effect.

You would, however, immediately turn the top card of your deck faceup as you are playing Erebor Guard with Gandalf’s ability, and that would allow you to decide whether or not you want to resolve the Guard’s Response effect.

Seems intuitive based on other FFG games.