Ryze's new passive with seraphs embrace and death cap...

So how does this work? Mathematically it seems like infinite stacking. Then again it could be like Vladimir passive. Or I could just be flat out missing something.

If you don't understand, Ryzes new passive gives 5% max mana for every 100 ap. Seraphs converts mana into ap. Deathcap increases Ap which increases Ryzes passive.