The crew have pissed some Big Cheese off. He orders an expert sniper to attack one of them.
En route to the next score, he strikes: Sights-up from a long distance with a high calibre rifle and fires.
How to handle this?
Do it from the assassin’s POV. Treat him like a player with 4 on Hunt, say, and roll with that. And treat 6s & crits as “the target’s head is blown off”. The player will do a Resistance roll. of course, to save his life.
Do it from the assassin’s POV, but use Fortune instead. 4-6 as above. This might fit more with the game tropes, but to me doesn’t feel right. Blind luck is not an expert.
Do it from the assassin’s POV and just declare he’s so good, he hits automatically. Resist as above.
Do it from the target’s POV. He uses Survey or maybe Hunt to spot the killer. If he gets a Fail, then Resist head blown off as above, otherwise can dive for cover or get wounded.
Decide that you will treat this attack as a Downtime consequence, and handle it like option 3.
Personally I wouldn’t use any kind of “do you see something” -roll for players, it is kinda like perception check and I don’t think they fit in the fiction first playstyle that well.
Id go by the book:
a) If the assassin isn’t that good or situation doesn’t favour him, the PC’s spot him and get to act when he is setting up
b) If the assassin is pretty good, the PC’s will see a glint of his scope or birds flying off near his hideout or reflection in the window just before he is abou to squeeze his shot: they get to do something like dive for cover, maybe if they have firearms at hand even try to shoot him first etc, effect might definitely be limited or even no effect if you want to emphasize that the sniper has picked a good location with little opportunities for cover and so forth
c) If you want to emphasize the fact that the assassin is really really good then it is BLAM! and resistance roll.
Also if you intend to use him en route to score maybe you could keep him in the game as a clock and use him for consequences.
I’m pretty sure “The sniper has a perfect shot lined up” -clock on the table would raise tension and make players squirm:D
I would say that if the sniper’s really good, as you imply, then your solution 3 is the right one.
If he’s not that good, then Vcut’s solution.
But how do we know if the sniper’s good or not? Well, that probably depends from the Big Cheese’s faction tier. In this exemple it is logical that the Big Cheese would send one of his best killers, ie with training and quality equipment equal to the faction’s tier. So in that last case you could also do a Fortune roll, as in your point 2, but with 1 for luck + (difference in Tier between the Big Cheese faction and the crew) dice.
But for me it would be strange to have an ambush like this “on the way to a score”. How does the sniper know where and when they will pass on their way to a score? Maybe do the scene in free play, not during a score.
You could also have him just BLAM kill someone, but an NPC rather than a PC. You’re walking with someone, and suddenly their brains are all over you. That way the sniper is clearly competent, and the PCs have some warning before they’re killed. Maybe they’re walking with one of their cohorts or friends and the cohort gets shot in the gut. Cohort is bleeding out, and if you don’t get to them they die, but if you go to them, you expose yourself to the CLEARLY VERY DEADLY sniper’s fire.