I recently had an encounter begin with the players group unnoticed by a oncoming npc group. Having successful made stealth rolls they attacked from concealment in the near by tree line by the use of bows.

I looked through the rulebook to see how best to handle surprise like this, and the best I found was the addition of black dice to the npcs initiative. Is this the correct way to deal with it according to the rules ? . If so, I assume that means that the defending npc's would still be allowed the use of their reaction cards to defend against the arrows ? I also assume that with a lucky enough roll, the npc's could still go in front of the attacking players ?

I may have missed a section on this, so if so let me know. Still learning the system as we go

An example of how surprise can be handled is found in the first encounter for "A Day Late..." (downloads section), but basically if the PCs get the on the beastmen, the encounter text suggests adding a [W] to the initiative rolls for the PCS and adding a fortune point to the pool.

I don't think there is a fast rule for surprise in the rulebook, the above rule (or adding dice as you mention) works fine, i think.

If it was a genuine ambush, you could even give the ambushers one free round of action, if you felt the bonus to initiative wasn't sufficient.

p.57 - It's a purple challenge die added to the intiative of someone "ambushed", which you could use for "surprised".

p.60 - A white fortune die added for having suprise, I interpret this as being to initiative of someone with surprise, and also to their action if they still have surprise (go first)

I see this as meaning that surprise/ambush gives you a good chance of going first (between getting a fortune die and imposing challenge die) with the advantage that entails but does not guarantee it. Some folks are so fast/lucky that even surprise doesn't really slow them down that much (try surprising Batman). It's also not a "round of free actions", the other side still goes on their initiative.

If having people sneak around for suprise, also note the rule under Stealth skill that trying to stay hidden while making maneouvers costs 1 stress.

Rob

All good options and advice, the rule set is pretty free form in that sense. The GM can simply apply the rule he likes the most relevant to the situation at hand.

If you wanted to get somewhat more complicated (in addition to awarding fortune/misfortune) you could force an agility check for each group/individual being surprised. Successes mean they may continue to use their defenses, failure means you place two recharge tokens on each defense (dodge, parry, block).