found here: http://forums.synergiesmod.com/index.php?topic=820.msg6434#new
If that's the case, then Skull Barrage is affected by Focus, Strength *and* +Poison % Gear.
Simplified just a little bit, skills that do "X% Weapon DPS" do: (((A * B * C * D * E) + F) - G) * H damage where:
A is the "X% Weapon DPS" value from the skill
the sum base damage on your right-hand weapon, plus
flat +X <type> damage bonuses located on the right-hand weapon (vellique skulls, enchantments, etc.)
1 / the weapon's attack period, where
the weapon's attack period is already modified by increased attack speed bonuses
D is the sum 1 plus of all the following:
0.5% * Strength
0.5% Focus (applied **only** to the elemental components of your weapon's damage)
"+X% all damage" bonuses; "+X% <element> damage" bonuses (each applied **only** to the corresponding elemental component of your weapon's damage, if there is one); "+X% ranged/melee weapon/wand & staff damage" bonuses (whichever matches your weapon); "+X% damage while dual wielding" bonuses (if dual wielding); etc.
E is J * K where:
J is your total chance to crit from both Dexterity and other chance-to-crit bonuses
K is 1 plus your total critical damage bonus from both Strength and other critical damage bonuses
F is flat +X <type> damage bonuses located on armor
a random number between 50% of the monster's armor value and 100% of the monster's armor value, where
monster armor is already reduced by armor degradation effects
H is 1 plus the % value for helper skills like Hailstorm that inflict the "monsters take X% more <type> damage" status
That's damage per hit. DPS is going to also care about the spell's cycle time, which is going to be improved by faster cast speed bonuses, unless it's got a fixed cooldown.
Improving any of these variables is going to improve the damage you deal with skills that do "X% Weapon DPS."
Skills that do "X% Weapon Damage" work exactly the same except that C always equals 1.
Skills that do "X% Weapon DPS as <element>" work exactly the same except that you ignore the original damage types on your weapon and pretend that they are all <element> damage from the start.
From here: http://forums.runicgames.com/viewtopic.php?f=30&t=50634