Mid-lane assassination and lane safety.
Burst damage and target access
Hitting a champion with 3 separate attacks or abilities in 2s deals bonus adaptive damage.
Gain a burst of Lethality and Magic Penetration after using a dash, leap, blink, teleport, or on leaving stealth.
Collect eyeballs for champion and ward takedowns. Gain permanent AD or AP, Adaptive for each eyeball plus bonus upon collection completion.
Heal for a percentage of damage dealt with your abilities. Increases with each unique takedown.
Creative tools and rule bending
Gain a free stopwatch. Stopwatch has a one time use Stasis active.
+5% Max CDR
+5% Summoner Spell CDR
+5% Item CDR
+6 AD or 10 AP
+5 Armor or 6 MR (match-up)
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.
Eyeball Collection's ability to assist you in snowballing an early kill is great for solo queue.
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.
Zhonya's pairs extremely well with Ekko's ability kit as it allows him to buy time for the perfect Ultimate or [W] stun to get out of a sticky situation.
Cosmic Insight's extra CDR is fantastic for early game skirmishes where an extra ability cast can be the difference between life and death.