Draba timing

Situation: A → B → C
A plays Magic of the Smith at 3 stealth, B has a locked Prince and a Second Tradition: Domain in hand.

Must B declare wether he attempts (using Second Tradition) or declines to block before C has a chance to play Draba ? Can he wait to see if C plays Draba and only use his Second Tradition in this case ?

Relevant ruling (maybe): [PIB 20150820] .

Bonus questions:
- Does the same timing apply for C to use an inferior Draba on A's vampire ?
- Does the same timing apply to Ignis Fatuus at inferior and superior ?

The situation happened in game and we were curious to see if B had to commit and trust the Ravnos player, which is not the same as waiting for after he plays the card.

---

So in teory :
Situation: A → B → C
A plays Magic of the Smith at 3 stealth, B has unlocked minion,0 intercept,B can ask player C do you have Draba to help me,if C say: yes I have and want to play,B can declare atempt to block even with 0 intercept and him expect to C play Draba when C get impulse?

Yes. There is nothing stopping you from declaring an attempt to block while you do not have enough intercept. Technically, you do this all the time. You cannot play intercept you do not need, so in order to meet that requirement you must attempt to block with insufficient intercept.