If your participating character dies somehow while in battle, can you still play character cards matching your _leader_ during that battle? It feels like the intent might be yes, but perhaps reading exactly to the letter, it could be construed as no.

Once they're dead the battle'd be over anyway, right?

RAW seems to be no, I was on the recieving end of this with my arya card supporting I wanted to play her leader card at the end of the resolution phase, but the Challenging player first triggered Olena tyrells leader card and my arya only had 2 power at that stage, and so she died, before my card could be played.