I'm talking about 
. These are two unique and situational stats. You shouldn't need to purchase both together in an item. This is as opposed to other less situational stats such as CDR, which you will benefit from almost unconditionally. These two stats should be split up and placed on separate items.
Just like how armor pen and grevious wounds isnt on the same item right? 
I can think of plenty of instances where both of those would be useful. Why do you believe they are not?
How is CDR situational? Name a situation were having your skills coming off CD faster is a bad thing.
Nah just reverse the stats so 
gives grievous wounds (Maybe with the old <30% health only condition) and Magic pen isn't granted until the final item. This fits in line with Physical casters and ADCs having 
and tanks having 
as early options for the stat.
If mages want to rush MPen they can rush boots.
