Okay so Im just copying pasting a topic that neurapraxia posted a long while back.
Spell Resistance and how it stacks. I’m not entirely sure how the items are set up, if they’re all the same type of magic resistance then they don’t stack (highest ranking magic resist item is the form of magic resist you have), and that would leave you with only factoring in the two forms of resistance, if they do stack you would simply add S3 part to the equation. Any way you look at it magic resistance stacks with diminishingly returns.
Spell Resistance = (1 - (1 - S1) * (1 - S2)) * 100 and so on and so forth. If Glorn adds a hero with a resistant skill to spells simply add another *(1-S3)) before the *100 .
Hero natural resistance and with Set Armor or Spiked Gloves
(1 - (1 - 0.25) * (1 - 0.20)) * 100
(1-(.75)*(.80))*100
(1-(.6))*100
(.4)*100
which gives us 40% magic resistance not the 45 like some would like to imagine.
Hero natural resistance and with either Cloak of unseen or Cloak of the Hidden or Gloves of Death.
(1-(1-0.25)*(1-0.50))*100
(1-(.75)*(.50))*100
(1-(.38))*100
(.62)*100
Which gives us 62% magic resistance. Again notice its not the 75% like a lot of people would like to imagine.
Hero natural resistance and with either Black Knights Mail or Immortals Boots or Immortals Shoulders.
(1-(1-0.25)*(1-0.75))*100
(1-(.75)*(.25))*100
(1-(.19))*100
(.81)*100
Which gives us 81% magic resistance. Once again its not 100% like way too many seem to think
and his second double post.
So to add on for kicks lets see what the absolute maximum magic resist we can have in our beloved cha. Heroes Natural Resistance, Black Knights Mail (or Immortals Boots or Immortals Shoulders) and Defend at Level 12. Here is the equation (1-(1-S1)*(1-S2)*(1-S3))*100
(1-(1-(.25))*(1-(.75))*(1-(.85)))*100
(1-(.75))*(.25)*(.15))*100
(1-(.03))*100
(.97)*100= 97% the absolute highest amount of magic resistance in cha.
