how to make Armor % reduction reduce spell damage?

My game is mainly based on spell casting, and i would like the spells to be reduced on the armor just like normal damage does.
a spell wich does 200 damage will do 200 damage on "Normal Defense" no matter what the % reduction given by the armor number is. i need to make all my spell damage do NORMAL damage.

how can i do this?

Sry, missunderstood you, like anitarf said in the next post

By making triggered spells with triggered damage, or by making a triggered spell resistance system using spell damage reduction abilities.

Or much easier, give all units a version of the item spellresistance ability of 101 levels 0-100% resistance. Then use the official formula to set this ability to the correct level:


That is, 1 armor gives 6% (level 6) of the ability etc.

It can be further improved by using two abilities of 21 levels each, -10% to 10% and -100% to 100% (so that you can add them together and avoid having hundreds of levels of an ability)

Better yet, would be a binary system, allowing -100% to 100% with only 8 abilities.

And that is better than one with two levels giving -100 to 100? How do they stack, by the way? I thought that when they did stack they had diminishing returns in % terms (but exponential returns in EHP).