Synergies.

[Roland]

- Does it have to be a bonus to something Vengeance already does (+AR, +elemental damage based on physical damage, mana cost) ?

One look at Cleansing or Meditation will tell you that it doesn't have to be something the skill already possesses. You could give Fanaticism LifeSteal by giving it a synergy bonus from, say, Conversion, or something like that. So, no, you don't HAVE to boost what it already has. It's just easier, and typically is the better, more logical choice. But not always. ;)

- Or can it be something different like +ias ?

Untested, but I don't see why it couldn't.

Synergies can provide any number of bonuses, but it is still VERY early into the beta to know all the answers. Plus, you have to keep in mind that any and all of this could potentially change by the time we get the official, final release, although it's not likely. As I dig further into the files, and practice more, I learn more, and thus am able to grasp a better understanding of how synergies work (and, for that matter, what works and what doesn't ;)). When WarBlade said Blizzard rolled two auras into one (Cleansing + Prayer, and Meditation + Prayer), he didn't know exactly how dead on he was. In the file, all it did was put in an entry to use Prayer's exact healing data along with whatever the aura normally gives. A bad move, IMO, as it makes Prayer even more worthless now, but so it goes. It's easily rectifiable, to a modder such as myself. ;)

I will say this:
Where once there was mainly one .txt file that governed most of what you could, and would, do concerning skills, there are now three .txt's. The original file (skills.txt) got a HUGE overhaul, and is now linked to two other files. This doesn't mean a thing to your average gamer, but to a modder, it's a dream come true. Swapping skill effects, or even creating whole new skills is a cinch now, whereas before it involved code-editing and was a headache. In addition, that overhaul to skills.txt turned what was once a fairly simple file into a boatload of Nordic runes and Egyptian heiroglyphics. :P So, it's taking a bit of time to decode all the new columns and entries, and just what role each plays. A mathematician / programmer would probably have a field day with all this. ;) And, someone well versed in math will have a hell of an easier time dealing with the new formulas, as it is very math-intensive. :D

My general plan is that, for skills with multiple bonuses, I'll seperate the synergy boosts to those bonuses among the different synergy skills. I.e. Fanatcisim may get an AR boost from Blessed Aim, a speed boost from Might, and a damage boost from Concentration. Might, OTOH, will most likely just get varying degrees of bonus damage based on the synergy skill. This will create greater diversity, and keep a leash on synergy-boosted skills, so that they don't become too out of hand. Of course, the greatest way to do that is to limit synergy bonuses to being based on the BASE skill level of the skills, rather than the total level - which is exactly my plan. :) See my notes in a previous post for more on that.