Ekko; Master of time.
I know Ekko will probably be nerfed here soon. But as it stands, I think he is one of the best champs Riot has done in awhile. Using him right will make your burst deadly, and as I did, you will fall in love.
So we start with Q, and we poke. I'd recommend focusing minions and trying to be safe. Money is Key with Ekko. Remember Q does Damage Both ways, Forward, and backward, also marking the enemy. With 2 marks, your 3rd attack with do deadly damage. Level 3 is an O.K. fighting leveling, but I'd wait for 6 at least to go full in. Get enough farm to at least get Amplifying Tome, and Boots. (Note: Please if you can get enough farm and get Mejai's Soulstealer (1400G) early, Take this route, as it ensures you will be ahead) You will then sell this item later in the game.
Should be level 4-18
Ok so you have gone base, got some items, and refilled your health. not what. Well, its the fun time, as I said, Focus money, get kills when you can. the best advice i can give you when using Ekko is, set W in an area you want to fight and trap the enemy (As it stuns and shields you after a period of time), then push them toward it with E moving in a way it will make then run toward your W. then use this extended Attack range to leap to them. by now, your W should have ended, giving you a shield, and stunning them, and this leap would have been your 3rd attack, doing deadly damage. Depending on your life, and your opponents life, you can stay auto attacking and do a little damage, as this will ensure the best part of Ekko. I'm sure you noticed that shadow of yours following you everywhere but doing nothing. Well if you can get that to catch up you you while Auto attacking, and then R, you will get your life back, and Should Kill your opponent. This is the Key to Ekko, using and timing. As he is the Master of Time.
Items, Runes and Masteries
With this Guide, and runes and build. I haven't lost a game yet. Ensure you follow Build Items in Sequence. (Very Important) Also, Having Mejai's Soulstealer early game almost ensure your win, or at least getting fed. Remember to switch item build if you wind up getting behind due to a camping jungle or very good mid laner. the only item i haven't tried yet early game that could be useful is Rod of the Ages. This could make you more Sustain, but I see it lowering your burst and slowing your build.
Pros / Cons
If you get behind, its very hard to catch up. That's why I'd say focus farming, get your kills when Jungle Ganks. Ekko has little Escape, but Tremendous Damage.
He can be the most Damaging person on the team when used right. My personal favorite Tactic, is to E into a big team fight, Zhonya's Hourglass so Shadow Catches up, and R, when whole team is there. The damage is Outrageous and you will have gotten life back. (Note: I RECOMMEND TO ONLY DO THIS WHEN FLASH IS UP, AS THAT WILL BE YOUR ESCAPE FROM ANYONE WHO LEAVES, AND YOUR TEAM CAN FOLLOW UP.) Q as well AFTER flash, to slow anyone who follows!
Creeping / Jungling
Ask Jungle for Blue when possible. And if you plan to take on a Camp in the jungle, Start fight with W, and then Q. Start auto and you will be shielded threw fight. this way a camp doesn't take 50% of your life.