ToME: the Tales of Maj'Eyal

I'm a pretty new player and I'm still wrapping my head around damage modifiers. I'm playing as a skeleton archer and I found a robe which says 'changes damage: 30% nature.' I also have another item which says 'changes damage: 10% lightning.' Does this mean that when I attack, my attack will do 30% nature and 10% lightning damage? Isn't this bad because if i'm up against a resistant to nature enemy, i'll do less overall damage? Can someone explain this to me as I went on the wiki and I still dont understand this. Thanks everyone!

damage modifiers don't change your damage type. They only increase any given damage type. if you have 30% nature damgage modifier, you will deal 30% more damage if you use nature. What you are thinking of is damage conversion, which is much more rare. basically, having damage modifiers of different elements to what damage you deal will not hurt you, but it won't help you either.