Player 1 has Catelyn Stark with Nymeria attached. Lets assume Player 2 mounts a sucessful military challenge, and player one has to decide which character to kill.
According to the cards, Player 1 can choose Catelyn Stark, then kneel Nymeria to prevent Catelyn Stark from being killed.
Both players are new, so it appears to us this prevents Player 2 from ever causing Player 1 from ever having to actually kill off a character after losing a military challenge.
What we we missing?