ok so now my 2nd question. Would the +10-35 magic damage +10% magic damage jewel mess up a barbarians zerk if socketed in a helm like hellwarden's will
It really shouldn't they are completely different affixes and damage calculations but you might want to test it
There's also the question if +% magic damage works, we didn't have that before and berserker is a skill that converts physical damage to elemental damage
Cold arrow for example converts physical damage to cold damage, but
does not work with +% cold damage (which only applies to its added +cold damage)
I believe based on that, +% magic damage should NOT work with berserk, but -% enemy magic resist will. Which makes it pretty obvious which version of the jewel you want, since that would be better anyway