Minor elemental tests (mostly for the FAQ, but this has DL utility as well):
(ATK - DEF)*some number = damage. Some number depends on elements, and it's what I'm trying to figure out. This assumes physical attacks unless I state otherwise.
1. White Dragon (281 ATK, 125 DEF, 1 White, 1 Red) vs. Hellhound (207 ATK, 105 DEF, 1 Black)
WD: 176 [219]
(1.25)
Hellhound: 82 [100]
(1.22)
2. White Dragon (281 ATK, 125 DEF, 1 White, 1 Red) vs. Demon (207 ATK, 110 DEF, 2 Black)
WD: 171 [213]
(1.25)
Demon: 82 [109]
(1.33)
3. White Dragon (281 ATK, 125 DEF, 1 White, 1 Red) vs. Dryst (268 ATK, 135 DEF, 1 Black, 1 Red)
WD: [146] 151
(1.00)
Dryst: [143] 147
(1.00)
I chalk the differences here up to random variance.
4. Coel (196 ATK, 81 INT, 115 DEF, 2 White) vs Hellhound (207 ATK, 37 INT, 105 DEF, 1 Black)
Coel: 91 [122]
(1.34)
Hellhound: 92 [113]
(1.23)
Divine Ray (3 White): (81 - 37 + 180) = 224 [317]
(1.415)
5. Coel (196 ATK, 81 INT, 115 DEF, 2 White) vs. Demon (207 ATK, 79 INT, 110 DEF, 2 Black)
Coel: 115
(1.33)
Demon: 122
(1.326)
Divine Ray (3 White): (81 - 79 + 180) = 182 [257]
(1.412)
Conclusions: Elemental spheres deal damage in this fashion:
1: ~25% more
2: ~33% more
3: ~41% more
The element of the attacker/spell (in GE, spells have their own elemental properties) is the main factor in elemental damage bonuses. As shown with tests against the Hellhound (1 Black) and Demon (2 Black), the multiplier is applied whenever you hit an elemental weakness, but the damage does not increase even if the target has differing amounts of spheres in an element.
This means that more spheres in an element contribute more to offense than defense. Three spheres in a color increases damage by 41% against an opposing element, but it does not intensify the weakness for that element.
In the White Dragon (1 White, 1 Red) vs. Dryst (1 Black, 1 Red) case, the weaknesses caused by the white and black spheres were cancelled by the two reds.
I'll look into other elemental stuff (like same vs. same) after my finals.