This got changed at least a couple times this edition, but as it stands - if you don't have LoF to an enemy trooper, can you declare a BS attack at them, and then if by the time resolution kicks in it's legal does it work?
Following - as far as I know people can't agree on this and there hasn't really been an official ruling. I think you can declare without LoF (e.g. through smoke), but the argument seems to be over whether or not total cover prevents declaration or if that rule was intended to be superseded by the newest FAQ.
Aight glad I'm not the only one who's confused. Also, is white noise different because it creates a zone, as opposed to being an attack? Who knows?
You can declare BS attack as long as the target isn't in Total Cover because that stops declaration. LoF is checked during resolution.
Q: How do LoF and ZoC Skill Requirements work? A: LoF Requirements must be fulfilled when declaring Skills. ZoC Requirements must be fulfilled during the Resolution step. I found this on the wiki page: https://infinitythewiki.com/Trooper_Activation#Order_Expenditure_Sequence EDIT: ok, ignore that. The Sequence and the FAQ entry on the wiki seems to be outdated and FAQ 1.1 overrides this: https://downloads.corvusbelli.com/infinity/faq/n4-faq-en-v1-1-1.pdf Please, CB, update the Wiki!
Others have answered the content of the original post, and as for the question in the title: you can ARO-bait through smoke/0-v if you use a hacker without MSV. The Hacker is replaceable with Pheroware or other attacks that aren't a BS Attacks. MSV Hacker is replaceable with non-MSV Hacker through White Noise against a target with MSV. That's about it, though.
do you have an example? I assume I could declare a BS attack ARO against that Hacker, but if the Hacker then declares Hacking as her 2nd action, my BS ARO will be an idle during step5 of the resolution phase, right? But if the Hackers declares a BS attack instead as the 2nd skill, my BS attack ARO would still be valid?
Fixed a typo on "without" in my post. Yes, you got it right. The key part of zero visibility zone is that you're allowed to shoot through it without line of fire if you are attacked with a BS Attack. My bad, I remembered only the Comms Attack label, forgot they're listed as BS weapons!
The rules define "Cover" as "The term Cover refers to all pieces of scenery that partially or completely obstruct LoF, thus preventing the attacker from making a clean BS Attack." A White Noise zone isn't a "piece of scenery," so no, it blocks LoF but doesn't provide Total Cover.