User blog comment:AlexHawks/Challenge the meta - Support in the MID lane/@comment-4636093-20130426123701

Don't get Void Staff on Soraka. It becomes more and more obsolete the more times you cast Starcall on someone.

Instead get Abyssal Scepter (in fact get this always). Pentration does not synergize at all with her reduction, but more reduction does.

With just 5-6 starcalls (4-5 with Abyssal aura) you can easilly get someone into negative MR, where penetration does nothing.

Liandry's Torment is a powerful item on her because of the passive, and FLAT penetration is more useful for longer, however stay away from %penetration.