My opponent running Cersei's Scheme and declares an intrigue challenge against me with Deadly. I block with Lyanna. Lyanna dies to Deadly. Which happens first? The plot or the text from Lyanna?

Followup - What would have happened if she had died for claim? Would that change the order?

Thanks

Both effects are passive and neither is "when revealed", so the first player chooses the order (note that Deadly itself is a passive effect, so the first player may have decided to resolve Cersei's Scheme's effect before it). Nothing changes if Lyanna dies for claim, because the only thing that matters is that the passives initiate in the same action window (challenge resolution here, because it's where Cersei's Scheme kicks in).

Flagrin said:

She is Moribund. She is actually participating in the challenge until it ends and she hits the dead pile. Someone can bring up the real timing structure to show you when she actually stops participating as I may be slightly off.

Keep in mind that if any Lord characters were participating and Lyanna is killed for claim, they just might prevent Deadly from applying if they are defenders(or if Lords are attacking, there might end up being a kill for Deadly). The order of effects is very relevant and the first player determines this order.

Thanks for the replies. I was going agains Lanni Kneel and they had me all but knelt out on a turn I had a 2 claim plot flipped. I blocked an Intrigue challenge from Qyburn with Lyanna hoping to stand my Griff and swing back with a Military on my turn. We weren't sure of the order of things but as it turned out from the replies we did well.