Talk:Rune/@comment-50.103.18.163-20111024192824/@comment-4182524-20111026195308

Not true at all. Many abilities do physical damage and therefore benefit from armor pen (even Yorick's ghouls benefit from armor pen). Champions with abilities that do % armor REDUCTION (urgot, wukong, trundle) also benefit heavily from armor pen since it's applied after the reduction and therefore gets the full effect. Moreover, 15 armor penetration from marks is pretty standard at high elo on pretty much every physical damage dealer.

However, many people have stopped running Arpen quints in favor of AD quints on botlane AD carries since they're stronger at level 1 before your laning opponents get >21 armor and AD quints have a lot of gold value for the slot. And if your champion abilities scales with AD but do 99% magic damage (Katarina) you're better off with AD (though AD kat is a bad build).