Board Thread:League of Legends discussion/@comment-25532677-20141013050627/@comment-1330314-20141029053337

Archsight wrote: The only problem I see with Sion is his abilities scaling on two different damage types. This limits his potentail damage output.

This is used on a lot of champions, especially bruisers, to control their ability-based damage. Mixed damage means that it's more difficult to counterbuild you, but also more difficult for you to benefit from penetration, which for a bruiser means they get to deal consistent damage regardless of what the enemy builds, at the cost of not being able to spec that hard into damage. If Sion were intended to deal more damage, or scale better with items, than that would warrant increasing the bases or ratios on his spells, but the fact that he has two dummy AP scalings means he shouldn't be focusing on itemizing for too much damage: his W and E don't scale well with AP because he's not meant to build AP or scale in ability damage other than through his bases.