Be Warned that this build is extremely squishy, even with the tiny bits of armor from seals and HP from Rylai's. Please play cautiously with it. This was written as my attempt to get a near full CDR while keeping Ezreal's money needy start satisfied.

686AP 39%CD. Just what I was looking for. I know that more AP could be reached but the utility from Rylai's is invaluable. At lowest levels mana may be a slight issue but by the end its difficult to run out so i decided against switching seals to mp5. Also Deathfire late means that the CDR we want isn't achieved until end game which is a little depressing. If you really want to reach very near 40% without going over you could make an entirely CD runepage and buy a void staff instead. However I like starting with 44AP and good penetration on it. A better alternative may be to buy the tome before archangles giving you MP5 when you may still have use for it and keeping 34%CDR sooner. As usual EZ needs to build up a good bit of foundation with the necessity of sheen and overall unbeatable value of archangles.

Other considerations are to use gold/10 quints to get end game early, and take majai's if you're feeling good. I take the ghost mastery for dominion and the exhaust mastery to help against pesky stunning melee like panth or jax who might try to keep you in hitting range or to prevent runners early game.

I don't take utility mastery because I don't expect to have blue at all times, often other teammates may need it or it might be taken by the enemy. I've built this to make the buff unneccessary, be a pal and share with the rest. for dominion ghost might be worthwhile so feel free to switch the time dead mastery for improved ghost and replace improved exhaust with deadliness just cuz.