So here goes my first "guide". I'll update the items for every item i think will be viable for this Ekko. I'll keep practicing this Ekko before i get him into ranked. This "Guide" is still a work in progress. Ekko would be a great pick if you're team has not enough AP's or has already a tanky jungler or support. Ekko is rarely seen in the top lane ( and mid lane for the moment ) most top laner don't know how to handle an Ekko. Take this as your advantage.
Don't hesitate to leave feedback, express as you wish but be constructive.

+ great burst with passive
+ Very mobile
+ Easy Escape
+ Easy Carry

- Very squishy
- hard to use ulti in teamfights

The 18th point in cunning ( Thunderlord's Decree ) deals great damage with your passive in teamfights, whilst gaining the bonus damage from your passive you deal extra damage in aoe.
As first choice in the ferocity tree you can also pick the Attack Speed for long trades.

for the CS you can use your passive on the melee minions, and the cannon. For the ranged minions it is better just last hitting them without trying to push.

I first max the Q for it's cd rate, and his easy harass. Followed by the E to easily hit with the Q on it's come back, and then you can get your AA to activate your passive and get a nice burst. Since Your W is pretty hard to use I max it last, but if you're jungling it mayb be better to start with your W for the free stun.

Just take it, don't ask questions. ;)
great if you wanna tp to the botlane for some kills/assists
if you wanna dominate the other top laner and make sure you get those kills

I personally pick tp, even though it got nerfed. It fits better my playstyle.

The tunderlords is now the only keystone used for everyone ecepts supports, no needs of changing the masteries.
The runes don't change with the patch 5.24.
The tp ( teleportation) isn't that great anymore, but still a great pick, try ignite out if you think tp isn't worth it anymore.
I might set up a tanky build to bruise for your adc.
That's all for the moment.