you will play very good champion but it is little hard to play him. ezreal is one of the best ad carry. follow my instructions and you will be the best ez ever.

use masterries 21 0 9. it is the best chice for ad

armor penetration runes are great for farming and playing against champions with low armor. mana regen is important beaucuse ezreal have to spam by his spells, and health... it is needly for everyone.

the best is flash with exhaust.
you can also take flash with ignite

for farming use mystic shot. it will intercease your attack speeed. if there is a lot of minions near the turret use your ultimate. you will gain a lot of gold and you will save turret.

you should be great carry and you should we happy of that i let you know my build