How does sniping (stealth) function?

[SangoProduction]

So, you take a -20 to your stealth roll after attacking. You net a result of 5.

Now what? Do they need to actively roll perception? Or do they get the reactive perception check, due to your stealth attempt?

[Paragon]

So, you take a -20 to your stealth roll after attacking. You net a result of 5.

Now what? Do they need to actively roll perception? Or do they get the reactive perception check, due to your stealth attempt?

As I understand it, you need to be hidden before so they already rolled their Spot against your Hide and failed.

The snipping (stealth) function allows you to, maybe, not get noticed after attacking which you would have been if you didn't try it. In essence, you lose your move action to get away and gain a move action "hide in plain sight" exception