I have a question about the Timing of certain Action and ARO. Let's say a trooper A is behind a house, and an enemy trooper B activate inside the ZoC of A but without LoF to them. • B declare his first short skill, let's say Movement and this way enter the ZoC of A (but still out of LoF). • A declare his ARO, he could no do much since he cannot see B and A is not an Hacker. So what can A do? (this is the first question). For this example let's say A forfeit to ARO for this short skill. • B declare his second short skill, le'ts say Hacking. Or Pherowere Tactics: Endgame/Eraser . • A since he have forfeit his ARO in the previous step, now he can do nothing, so it will not a face to face but a normal rool?
As of the last FAQ, A can declare an ARO even if it is not valid at that step. If B then makes the ARO valid, it is triggered. This holds for everything except BS attack on a trooper whose LoF is completely obscured by terrain (but NOT by smoke). So in your example A should strongly consider declaring reset as its ARO, if a hacker or stink-magician enters its ZoC, as a prediction that it will become a valid ARO during the trooper's second short skill.
Moving into the ZoC of a model will grant an ARO opportunity unless you have stealth. In your example, I agree with Time Bandit in that the model would want to declare a reset as their ARO choice. Let's take this thought train a bit further down the rails as well, pretending that neither model is a hacker: Model B activates and declared Move, entering the ZoC of A but is out of LoF Model A declares dodge as his ARO, applying a -3 penalty because the target is out of LoF Model B declares move again, foregoing any kind of attack Model A rolls a 7, successfully dodging, and moves 2" to see around the blocking corner - now having LoF to Model B Just remember that being in ZoC allows for options, and doesn't always make the opponent forfeit their ARO
