Thanks for your comment. Trinity Force is amazing because of the 150% damage boost for Mystic Shot. If you've learned to use it's passive correctly you can deal a lot of damage. I also like the slow. It can ease escaping or chasing. Of course these items are not the only ones that are good for Ez but they worked fine for me and I think they're a good choice.

Mane regen and CD runes are fine as well. But I think you don't need them either. In late game I never had mana problems and the CDs are sufficient (all the more with golem buff). Moreover you will use Mystic Shot frequently, so CD is not much of a problem (-1 second CD of all spells).

The problem in late game is staying alive/avoid backports as long as possible to deal more damage and help your team. Your main item for that is the guardian angel. The runes will boost it's armor/magic res a bit. It's not intended for tanking purposes. It's just a bit more resistance if someone focus you (think of other range champs and so on). It won't help much against 5vs1 ganks and so on (but CD and mana regen neither).

But thanks for your notes. I will add some rune alternatives soon. ;)

Interesting guide, I see you put a lot of thought into it. I generally use most of the items listed aside from Trinity Force, since I've always looked at it and laughed. I'll give it a shot and return with feedback.

I'm not a fan of the rune build though, I've never seen much of an improvement with armor runes, even on my tanks. I normally stack mana regen and CD reduction (simply as there is nothing I've seen that truly benefits late game). Perhaps you can shed light on my ignorance?

Last note, I appreciate the calculations, they were very helpful.

Thank you for your comment.

Thanks to Ezreal's passive he gains +75% attack speed by hitting minions or champs with his abilities (full stacked). As you will spam Mystic Shot (or later Essence Flux at enemy champs -> 1 stack for each hit enemy) you will have this attack speed boost most of the time. Moreover Mystic Shot is not attack speed dependent and will be used as the main damage output. Trinity Force will also boost the attack speed a bit. Berserker's Greaves are an alternative for sure. Also Mercury's Threads and Ninja Tabi's but for me the Boots of Swiftness did a good job. The walk speed is horrible without. And when I get the walk speed bonus from Trinity Force I also get the attack speed bonus so it's no difference to buying Berserker's Greaves at this time (late endgame I think). ;)

I would Suggest Berserker Greaves, A lot of attack damage almost no attack speed added is a little bit of a let down but its just a suggestion and its not that much of a speed downgrade... Plus Trinity Force Kind of fills in for that missing 1 increased movement speed.