- You need to control a participating unique Lannister character at the time you would play Tyrion's Chain. So if The Hound was your only participating unique Lannister character, and you returned him to hand, you cannot play this event.
Reaction: After you win a challenge in which you control a participating unique character, choose a revealed War plot card. Initiate the when revealed ability on that plot card as if you had just revealed it. (Max 1 per phase.)