Spell Damage - Not working as intended?

Hi Guys,
I recently got a Clear Mind jewel with 48% increased spell damage to use with my Glacial Cascade Miner. I noticed that when I 'equip' the jewel, my damage only increased by 10-12% and not the 48% that I expected.

That got me started trying to figure out what is going on. I finally reached a point where I only had a wand equipped with 35% spell damage, and a lvl 1 Fireball spell. The wand only increased the fireball spell damage by 18%. Roughly half of the 35% that was expected. Granted, this was tested on a lvl 72 Duelist, but still, the mechanics should be the same as a lvl 1?

So my question is, why doesn't spell damage increase the damage proportional to its percentage (%) instead of mere 10-15% as it does now?

Thank you for taking your time to read this and offer help!

:)

Any stat worded "increased" or "reduced" is additive with other "increased" and "reduced" stats. So for example, say you have 100% increased spell damage, 100% increased fire damage, and 20% increased damage. All those numbers are additive, for a total of 220% increased damage on your Fireball (or 3.2 * base damage). If you then add another 20% increased spell damage, then that adds too, giving you 240% increased damage (3.4 * base damage). 3.4/3.2 is only about 6% more actual damage. That's what causing the numbers you're seeing.

By contrast, anything worded "more" or "less" is multiplicative with all other stats. If you take Berserker's Aspect of Carnage passive, which grants 40% more damage, your tooltip really will increase by 40%.

Hi Viperesque,

Thank you for a very informative, easily understandable, and quick response. Much appreciated!