Lord Doran's Chambers
You may choose to play Lord Doran's Chambers as an attachment to your House card.
Kraznys Mo Nakloz
Challenges: If it is Summer, choose an opponent's attachment in play. Pay that attachment's printed gold cost to take control of that attachment, and attach it to a card of your choice.
Could I take control of Lord Doran's Chambers and attach it on one of my character with Kraznys ?
I would say yes. And here is my reasoning.
Once Chambers are attached to House card, they become an attachment. And they stay as an attachment until the card leaves play.
The part "to your House card" is only a play restriction if you want to play Chambers as an attachment. This restriction applies only at the time the card is played but is not applicable after.
So Kraznys effect would allow me to take control of the Chambers and attach them to any card that can receive attachments.
By default, attachments can only be attached to characters, so I think I not only could but would have to attach the Chambers to a character.
Am I wrong?