Talk:Vi/@comment-87.163.159.198-20121221065027/@comment-62.226.34.175-20121221115022

2 reasons:

1. as stated, the Sheen-Items: champs with abilities that somehow work well with sheen often have an AP scaling, even it's just some minor scaling on the ult (renekton)

the mana on the other hand on those items is nothing that strongly encourages you to buy them on those champs, but to discourage building it on low-cd alternative ressources.

2. Baron-buff and Auras: so you can make use of poth parts of the Baron-buff, and AP is a stronger stat by itself through certain effects (hard scalings, rabbadons) AD champs get some additional minor buff. same for Auras like WotA.

to make it simple: an AP champ with Baron buff will deal more damage with abilities and autoattacks. A pure AD champ will deal more damage aswell, but would not profit in any way from the gained AP, leaving 25-50%(if they are manaless) of the buff useless on them. This rule has exceptions if the AD-champs are heavy burst casters with strong scalings (Riven, Talon, Zed) that profit from AD the way AP champs profit from AD+AP.