Talk:Magic penetration/@comment-91.183.32.144-20120509074110/@comment-4087140-20120510194250

Yes, the target does lose the same amount of effective health whether they are low-resistance or high-resistance, but the point is that the effective health difference is relatively larger against squishy targets. Here's a sample scenario; you have enough gold to purchase one of two items: In order to figure out which one will benefit you most, you must consider the armor of your intended target. If they have 200 armor, then your damage output will increase by 1(300/280) 7.14%, so you should buy item A instead. If they have 50 armor, then your damage output will increase by 1(150/130) 15.4%, so you should buy item B.
 * Buy item A to increase your damage by 10%.
 * Buy item B to penetrate 20 points of armor.

So it's not that penetration is actually "worse" against high-resistance targets, just that you can usually get other items that have a larger net benefit. Does this help?