Hi there, and welcome to my first guide on here. As he is a new champion and everyone rushes to auto-lock him in, those lucky enough to get him will have a good time. (Hopefully anyway.) I'll try to keep it short, sweet, and to the point. Also, I tend to play my Ekko like Diana, so if you're somewhat familiar with her then it should be a little easier to play as him. He's also a relative easy champion to grasp once you play him for a bit.

Here's a little music for the light reading.

I'm generally not a fan of Skrillex, but, I can understand if you're not.

: These runes are nice because of your AA. Also helps out Lich Bane with some damage if you choose to rush that before a Ludens.

: A basic but necessary rune. A little extra armor never hurt nobody, might even safe your life.

: I take three of these because that little extra health with these plus the one Quint can mean all that much more when you're running away from an attack.

: You could do these like me, or you could build more Magic resist if you want to be extra careful, or if you're going to have to up against an AP user.

:
A little extra boost in AS to help you set off your passive all that much faster in laning phase.

:
Like I said earlier, these are nice to start with in the beginning but, if you'd prefer to swap these and the seals with the scaling ones by all means.

For my Masteries I like to go with a 21-9-0 set-up, more will be added once I do some more testing, but for now these are pretty basic.
The four points in CD reduction is nice for getting your skills cooldown that much faster. Whether you're using your E for a chase or dashing through a wall to escape. It helps all the same.
The rest are your basic AP masteries in the first tier. As for the second, you take the general left quadront for the health increase and minion damage reduction.

I know most people don't really agree with having the Boots of Swiftness, but if you're doing good then take these. You'll laugh when you see how fast you go across the map. Also like these compared to Mobility Boots because of when you are in combat your speed just drops. I like a consistant rate of fun, combined with his passive for the movement steal, you'll love it that much more.

Rabadon's Deathcap: Pretty standard for AP's, once you have this you'll REALLY start to have fun.

Lich Bane: If you can get the skill to proc after you have used your Q>W>E Combo's they're as good as dead.

Void Staff: This baby is a must as well as Rabadon's, since we're not taking Sorc boots you'll need the extra MP Pen, and love it all the same.

Zhonya's Hourglass: Granted your R gives you a bit of minior one it never hurts to have a back-up for whenver your ult's on CD.

Spirit Visage: Besides having all the good things you could want in an item, why would you not take this? Unless you're going against a more AD heavy team, or would prefer the next item more.

Guardian Angel: Gives you that second chance to either fly away, or just wreck stuff.

Z-Drive Resonance:

Ekko's Zero-Drive charges his spells and attacks with temporal energy, making him build up Resonance stacks on enemies which last up to 4 seconds. Every third stack deals 15 + (12 × Ekko's level) (+70% of ability power) bonus magic damage and saps the target's movement speed by 40 / 50 / 60 / 70 / 80% for 2 / 2.5 / 3 seconds. If the target is a champion, Ekko also gains the same percentage of movement speed for the duration.

TLDR;

This passive is one of my favorites. It gives you an automatic slow, damage, and buffs your speed. It's sauceome. (Awesome sauce please)
Timewinder:

Ekko throws a device in a target direction, dealing 60 / 75 / 90 / 105 / 130 (+20% of ability power) magic damage to all enemies along its path. At maximum range or if it hits an enemy champion, the device slows to a stop and expands, creating a slowing field which slows enemies inside it by 32 / 39 / 46 / 53 / 60%.

After a short delay, the device contracts and rushes back to Ekko, dealing 60 / 85 / 110 / 135 / 160 (+60% of ability power) additional magic damage to all enemies along its path.

TLDR;

This reminds me of a SLOWER version of Talon's Rake, when using this skill Upgrade this skill first and max first. This will be your ranged poke. Always start a fight with this and try to get infront of them for the return.
Parallel Convergence:

Passive: Ekko's basic attacks deal bonus magic damage to enemies under 30% health equal to 5% (+ 1% per 45 AP) of their missing health (max 400 damage vs. minions and monsters).

Active: After a 3 second delay, Ekko creates a short-lived chronosphere at the target location that slows enemies who enter by 40%. If Ekko enters the sphere, he will detonate it, gaining a shield that absorbs 150 / 195 / 240 / 285 / 330 (+80% of ability power) damage for 2 seconds. Enemies caught inside are also stunned for 2.25 seconds.

TLDR;

Awesome passive, a little OP with the scaling at (+ 1% per 45 AP). Abuse it while you can. The Active is crutical for your burst combo, with 80% scaling for your shield it'll help loads. But, don't blink or you'll miss it.
Phase Dive:

Ekko dashes a short distance in the targeted direction. He gains 300 bonus attack range on his next attack, which deals 50 / 80 / 110 / 140 / 170 (+20% of ability power) bonus magic damage and teleports him to his target.

TLDR;

What it doesn't tell you is that you can use this to dash through small walls to gank or evade. Scaling isn't the greatest but, it's fair. Also, it's your first escape or chase tool.
Chronobreak:

Ekko shatters his timeline, becoming untargetable and teleporting him back to wherever he was 4 seconds ago. Ekko heals himself for 100 / 150 / 200 (+20 / 25 / 30% (+ 1% per 30 AP) of the damage taken over the last 4 seconds), and deals 200 / 350 / 500 (+130% of ability power) magic damage to all nearby enemies on arrival.

TLDR;

Once you use gain your first point in this skill at six, you'll get the Prince of Persia skin joke if you didn't already. Forces you to keep an eye on where your shadow is so you can use to escape an ult or just to even damage. Also, four seconds doesn't seem like a lot but, later on you'll notice the difference.

Combos:

So, depending on the situation you are in depends on how you want to start things.

If you're going to initiate a fight, or gank:

W>Q>E>AA The return from the Q from where you're placed will either kill, hurt, or slow your prey so you can kill them soon.

Q>W>E>AA Same as above but this will help make your slow and stun more secure.

If you're being chased, and your trail in near them:

R>Q>W>E>AA Then burst from your ult, combined with your next few skills will melt anyone who is unfortunate to chase you down.

Tips:

By using your E, you can use it to dash through shallow walls for a quicker escape, gank, or set-up.

Your ult can successfully block most other ults that would kill you otherwise. Ex. Caits ult. Which in return will do an auto-taunt.

For clearing your creep waves, what you idealy want to do is time it so your Q can hit the entire wave when it goes out and on the return, after you get to level six you'll have two marks on them and you can hit them with your AA and one hit them for the easy money.

Jungling:

Traditionally, our Top is our buddy, our rock for our team. So how do we support said rock? Well, we start with Golems first. You don't need a leash to jungle with Ekko, infact you can get to wolves without needing to back, but, you'll be too weak to gank. So, if you ask nicely and get a good enough leash you can have your ADC and Support help you to clear them faster so you can improve your time as well as help everyone out when they ping for you.
The order I like to go in depends on the side I take, you'll always want to start bot then work your way top. So, on the blue side we have Golem's, Red, Blue, Gromp, wolves, then back. On the Red we'll take Gromp on first smite him so we can get his buff, then Blue, Red, Golems, and then Raptors. It'll leave you around level four, and will a decent amount to start you off.

TLDR;

Blue: Golems, Red, Blue, Gromp, Wolves, then go back at level four.

Red: Gromp, Blue, Red, Golems, Raptors, then go back at level four.

Note: If you're too weak to do wolves or raptors then just go back, because you don't want to get laughed at for dying in the jungle.

Overall, he's a very fun toon to play and has got an awesome sounding voice. Playing it safe until you're confident in the laning phase, and having good communication with your team will reward you with kills. Believe me, he can drop people like flies. Though, you'd want to stick close to your Tank/Bruiser to cast your W when the enemy squishies are grouped so when you can get them with the slow then your stun.

So, as this is my first guide, and the initial release of this post was rushed I'm sorry for everything that looks bleh. Long-time player, and long-time viewer. If you have any comments to say, please let me know your opinion.

Guide made 5/28:
- Updated guide.
- Added sections.
- Added CD Ekko.

Updates 5/30:

- Added Jungle Ekko.
- Added Combos/Tips.

Updates 5/31:

- Added AD Ekko.

Soon-to-be-added:

- Dominion guide.
- Twisted Treeline.
- AD Jungle Ekko.