Talk:Xerath/@comment-24531898-20140211014007/@comment-4881935-20140211014814

% Mpen stack multiplicatively with each other, and second, all the MPen gainned from runes are flat, not % so they are added different.

So for the % MPen, they stack as in:

(1-0.4)(1-0.35)(1-0.06) = 0.33 (ignored magic resit)

so you would effectively have 77% Mpen. Afterwards, what ever the remaining Magic resist they have, you would ignore up to the amount of flat Mpen you have.