this build is only really good on urf, as you will not get flamed for it

the reason for these specific items is you will be able to get over 1000 ap excluding his passive, the 4 [Rod of Ages] are to be gotten first, but after getting the first [Rod of Ages] you would want to get a [Tear of the Goddess] so that you can start stacking it, after either the second or fourth [Rod of Ages] you would want to get your [Archangel's Staff], last item [Rabadon's Deathcap]. The Passive alone from [Rabadon's Deathcap] will give around 250 ap, and the passive from [Archangel's Staff] will give around 120 ap. This build can be done on any champion, probably only should be done on ones that scale well with ap, and only on urf, the reason I say only on urf is because then you wont get flamed as often for doing a very stupid build. also the unique passive on [Rod of Ages] gives you some health based on the mana you use, but it is not very much.