Talk:Irelia/@comment-4829762-20120222175342/@comment-2124153-20120222185111

ArPen doesn't help you last-hit minions early on, because melee/caster minions don't even *have* armor until the sixth wave. It helps you again Siege minions and the enemy champion, and that's about it, because penetration can't take armor below zero.

So flat AD is much better for last-hitting. As a matter of fact, if you load up on flat AD Marks/Quints, and take +3 AD and +2 minion damage from tier 1 of the Offense tree, last-hitting becomes academic, Irelia is hitting minions for ~77 damage at level, basically. Under a tower, melee minions need 2 tower hits + 1 autoattack, and casters are 1 tower hit + 1 autoattack, no need to use Bladesurge at all. This is very convenient.

Flat AD also gives you a slight advantage when pushing down the enemy turret, since ArPen doesn't help you there.