Negative Elemental Armor?

I made a build and ended up having -300 on earth. Does it effect you a lot?

 

@LarzLapiz

 

I mean if you just don't get hit it doesn't matter right.

 

yea probably

 

So do you simply just take 300 additional dmg?

 

no its a lot more complicated than that

 

So it can deal much more than 300 dmg depending on the situation?

 

Yes the dmg calculation is weird, here's the damage that players take:
Melee Neutral Damage
(Base Damage) x (1+(ID Boost)-(Defense)) + (Raw Melee)

Melee Elemental Damage
(Base Damage) x (1+(ID Boost)) - ((Elemental Defense) x (1+(Elemental Defense %))

Spell Neutral Damage
(Base Damage) x (1+(ID Boost)-(Defense)) x (Attack Speed Boost) x (Spell Base Multiplier) + (Raw Spell) x (Spell Multiplier)

Spell Elemental Damage
{ (Base Damage) x (1+(ID Boost)) - ((Elemental Defense) x (1+(Elemental Defense %)) } x (Attack Speed Boost) x (Spell Base Multiplier)

 

What are the ID Boosts affected by or determined by?