Help about damage block

[JFAMAP]

Hello again. I wanted to learn something correctly.

Example i have a item that reduces 10 damage to %100 percentage
If i will bought another one it will reduce 20 damage ?

or

My second item is %66 percentage to reduces 10 damage
What is the my damage reducing now ?

I'm really confused about that

 

[shadowvzs]

first what you want do? because if u want manipulate critical/damage reduction/damage block/custom evasion or anything what modify the damage or related with damage then better use this http://www.hiveworkshop.com/forums/spells-569/gui-damage-engine-201016-post2043397/#post2043397

(i dont think its stacked, atleast for me dont worked the 2nd rune brance what must reduce the spell damage)