While above 70% health, gain up to +40 Ability Power or +28 Attack Damage (based on level), Adaptive.
Ekko can easily proc Electrocute with [Q] and [E], allowing him to burst down his opponent before they know what hit him.
After casting [E] Ekko gains both Magic Penetration and Lethality making his assassination potential incredibly high.
Zombie Ward allows you to keep wards up around mid-lane and provide even more safety in the laning phase.
if you're looking to snowball and carry early, Eyeball Collection is another good option here.
Like LeBlanc, Ekko massively benefits from Spell Vamp on his passive damage allowing him to sustain in lane and pressure his opponent.
If you'd prefer to have Zhonya's/Protobelt up more often Ingenious Hunter is a good option here as well.
Ekko is naturally a champion who is up front and center to proc his passive damage and land his [E]. As such he is susceptible to a lot of incoming damage and Nullifying orb helps you to fight through that.
Aboslute Focus allows you to front-load a lot of your damage into a high kill threat assassin play pattern.