Best shut downs for Ekko.
AP Warwick BUILD-

FULL AP Malphite BUILD-

there you go 
AP Warwick BUILD-

FULL AP Malphite BUILD-

there you go 
Asterisk*
*requires full build

That's a bad Malphite build. Try
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instead. It does a lot better against Ekko in particular and also doesn't waste 2900 gold on Liandry's (which is absolutely atrocious on Malphite). It offers much higher burst (which is the only reason to ever play AP Malph, if you aren't bursting, play someone else) and also uses items that are much more suitable to Malphite's style.
I think a strong jungle presence early is the key. Fiddlesticks will wreck him with the silence. That camp and forcing him to waste mana work well. Oh yea, take advantage of the fact that he is a melee farming champ in lane. Irrelia would wreck him. Get hit by q so you can proc the stun. Proceed to hurt him.
Ryze owns Ekko in 1v1's.
Sadly, Ekko can easily push the wave with just one Q.
Garen can outlast his mana and outpush him from 4 on, but unfortunately that means you're playing garen, and your kill potential is very limited unless he goofs because of ult.
I was sorta hoping for a in depth post here. The why or how ect. YAWN