100% Sorcery Shield Protection 

First you need to take the "Sorcery Shield" StoneHeart lost art to lvl 20 , this gives 100% sorcery shield ... 

Now you have to activate this protection ...

Activation Chance has 3 factors :

* 1st factor * : It's the number of beast riders you have in the army you will be using and the percentage those beast riders represent in the group ... Example : you are sending 1000 beast rider along with 9000 griffens ... total number of units is 10 000 ... thhe percentage the beast riders represent is 10%

* 2nd factor * : Is the "Sorcery Shield Chance" StoneHeart lost art ... gget it to lvl 20 and you will get 30% chance 

* 3rd factor * : It's the Champion of StoneHeart Activation Chance ...

How is the overall chance calculated now ? simple 

Chance = 1st factor percentage  MULTIPLIED BY (2nd factor percentage + 100% ) MULTIPLIED BY (3rd factor percentage +100%)

So let's say i have 1000 Beast Rider and 9000 griffens / 30% activation chance from lost art and an 94.5% Champion of activation chance ...

This will be my activation chance according to those conditions :

10% MULTIPLIED BY (30%+100%) MULTIPLIED BY (94.5%+100%) = 25.285% 

Not so great , and as you can see the 2nd and 3rd factor are almost constant and when maxed they become constant for good , so the most important factor is the 1st factor ... How many Beast riders you got and how much percentage tthey represent ...

Ok , HOW MANY BEAST RIDERS I SHOULD SEND TO GET A PERMANENT 100% CHANCE ???

Percentage of beast riders needed = 100% DEVIDED BY (2nd factor percentage + 100% ) DEVIDED BY (3rd factor percentage +100%) 

Let's try this with the same conditions we did before :

Percentage of beast riders needed = 100% DEVIDED BY (30%+100%) DEVIDED BY (94.5%+100%)= 39.54%      .... it means 3954 beast rider in each total of 10 000 troops (3954 beast riders+6046 griffens or other troops) If you get your Champion higher then the number of beast riders needed will drop 

Sor someone who has the 2nd and 3rd factor maxed to the top , he will only need 2881 beast riders in each total of 10 000 troops ... (2881 beast rider + 7119 griffens or other troops , all the 10 000 troops will be 100% immune to fireballs) That's the best one can ever get ...

And this is not "sometimes it works sometimes it doesn't" ... that's how you conttrol your activation chance !

Hope this helps