Talk:Magic Penetration/@comment-98.185.253.164-20101008084958/@comment-182.55.236.10-20110703202901

that would be 0 MR.

STEP 1: REDUCTION 40 MR - 20 (Abyssal) = 20 MR

STEP 2: PENETRATION 20 MR - 20 (Sorc boots) - 20 (Guise) = >0 MR == 0 MR

imo, still worth stacking mred with mpen, since it gives you the ability to pierce up to 60MR (most tanks get there). throw in a Malady and you can pierce up to 84MR. imo, this is why %mpen is weak: because MR values usually don't get too high (harder to stack MR), so Void Staff is really quite pointless if you have ANY mpen/mred at all.