Talk:Syndra/@comment-169.233.33.66-20130226060448/@comment-92.36.82.231-20130302233251

Because 15 magic penetration gives you about 25-40 damage on 800 damage spell (depending on resistance) and 75-150 on 3000 damage ultimate, while longer CD mean that you miss alot of damage that you could deal and worse, you may not have an ability in time when you need it. One second more on E can cost you a teamfight, and CD's always more noticeable than a few points of penetration, especially if you are a spamming mage. That's all about build in a nutshell, relying on variable factors like blue buff availability or vasting money on temporary boost from elixir (except for late game when you have full build and special situations) is not wise. You must have your CDR at all times no matter what.

BTW people building  Sorcerer's shoes on mages because mages are sorcerers and have to have these xD (because everyone is doing that, i. e. even when there are better options, LeBlanc is no different). Think wider.