A situation occurred the day playing against a friend and we would like some clarification.

I'm sorry if this is a long winded post. I will just explain the situation.

My opponent attacks with a mil challenge, it's unopposed I kill my house messenger, I respond with blood for blood to kill his carrion bird, he tries to respond with carrion bird's effect while it is moribund, but I thought that you can't use character response like carrion bird's until the sixth step of the challenge step after passive effect are triggered. Can he use carrion bird's effect?

Pffft. Long winded? Please.

Sounds like you played Blood for Blood too early.

Remember that challenge resolution goes like this:

1. Determine winner.

2. Resolve claim effects. <-- Your House Messenger died here for claim.

3. Award unopposed.

4. Award Renown.

5. Passives to everything in 1-4.

6. Responses to everything in 1-5. <-- So your Blood for Blood (death in #2) and his Carrion Bird (winning in #1).

7. End phase, physically remove moribund cards.

So, in challenge resolution with a Martell character dying for claim, Blood for Blood and Carrion Bird have the same timing and are played in the same step. You had to wait for passives before playing your event, too.

Thanks that was a quick one

FAE 1 (Steps 1,2,3). Determine winner.

FAE 2 (Steps 1,2,3). Resolve claim effects. <-- Your House Messenger died here for claim.

FAE 3 (Steps 1,2,3). Award unopposed.

FAE 4 (Steps 1,2,3). Award Renown.

Step 4. Passives to everything in current and all previous steps.

Step 5. Responses to everything in current and all previous steps. <-- So your Blood for Blood (death in FAE #2) and his Carrion Bird (winning in FAE #1).

Step 6. End of Action, physically remove moribund cards.

Pardon the OCD, but it bugs me to not have the remaining steps (passives, responses and end FAW) not be listed as 4, 5 and 6 as they are in the FAW/PAW diagrams. Here is my attempt at trying to come up with a way to show each Framework Action Event has it's own Steps 1,2 & 3 as well as showing the remaining steps.

Side note, regardless of how the carrion bird dies - provided it was during this final Framework Action Window - he can still trigger the birds effect even when moribund. This is because the effect itself doesn't require the bird to become moribund and the player has met all the other criteria.