First things first, thanks for reading and voting!

Rod of Ages is a very viable choice for AP Cho'Gath. That said, I don't think it has much of a place on tank Cho'Gath because it doesn't actually make you that much harder to kill. 650 extra health is not going to save you if your resistances are so low as to allow the opposition to burn right through it. Furthermore, you shouldn't have mana problems even without the extra mana from the rod. Lastly, the AP is not that much and you get a quarter of it over a period of ten minutes. For a comparable amount of gold, I could have a Rylai's Crystal Scepter and proc that awesome slow. I'm getting 150 less health and all of the AP of an RoA up front rather than in ten minutes, plus there's a useful passive that makes my aggressive plays more dangerous to my enemy. In short, RoA is a lot of passive stuff that doesn't help you win all that much and does not protect you from enemy damage the way more armor and MR do.

i like rod of ages for cho, it gives you good stuff but nice build, good work... like it +1