Better than i realized, yet still pretty stupid.

You'd be giving up 60 ability power plus the percentage gained from the mana along with that sweet ass shield. And all for what? For a glass cannon build? ON RYZE?

Ryze isn't bursty and his range his utter shit, his mobility ain't that great either even with the ult. Muramana would be good for dueling, maybe slightly useful for early game but mid and late game it would fall off hardcore and i'm not convinced you can even reach the 750 mana before laning phase is over.