Edwards amazing. So I made this guide. Because Edward is amazing.

Health Quints for easier trades.

AD Marks for AA harass. Hybrid Pen works good too IMO.

Armor Seals. The standard for every rune page.

AP Glyphs To boost your ability damage.

Masteries are mainly focused in defense. Makes trading in lane ridiculously easy because you have more survivability. and most importantly helps you survive engages for team fights.

9 in offense for a little more damage. and some CDR. All the CDR you're going to need honestly.

You start with a Dorans Shield of course. and a hpot and your ward trinket. No Need for a gp10 Item. I'll explain later.

From there you should rush sightstone. Maybe you could pick up boots before sightstone. if you find it to be necessary. But seriously. Get a sightstone. You're a support carry. a SUPPORT carry.

Switch your trinket to scanner after you get sightstone. upgrade your trinket and sightstone to ruby whenever as long as it's after your sorcs, rylais, and haunting guise.

You should eventually upgrade those boots to sorcerers. because mpen is amazing. (also I prefer the homeguard enchantment.)

From there build haunting guise. Because Health, Penetration, and AP.

From there build Rylais. Because Health Slow, and AP.

Then a Void Staff. Because Percentage Mpen and even more AP.
Pretty much your build is all about health ap and mpen.

If you manage to get to the point where you need a 6th item. Then this last item is your choice. I feel like you could honestly pick whatever you want. Depends what you're facing.

A lot of as on enemy team and you need more utility? Rands Omen
You want more damage? Rabadons
You need more health and armor with some aoe damage? then go for the sunfire. a great choice with all the penetration you have(helps thornmail too)
Need armor and survivability but more damage as well? Zhonyas
Need mr and even more penetration? Abyssal
more health and mr? spirit visage or banshees.
Just a ton of health? warmogs. why not.

Normal skill sequence. gives you the most damage. no need to explain.

Ignite/Flash is the way of a Grown Man.

Pros:
Safe Poke
Awesome Trading
Fairly Easy CC
Good Engage
Good Disengage
You get to feel like Edward

Cons:
Not much really.
No GP 10 Item.
No Shurimas.
More cons explained in Team Work.

So it's extremely important to realize. Kennen isn't a go to support that works with any team comp. As I said before. Shurimas is not a buy for kennen. It's just not worth it. so therefore you need a team that could follow up on your engages. Such as Kha zix, warwick, shyvana, or vi. Champs who could go in. and go in fast.

Also Sivir is a fantastic ADC for kennen. You'll have that MS boost for your whole team to catch up when you engage. Jinx works great thanks to your stuns. Lucians great too. great poke. And then theres varus. Who feels perfect with kennen support. Just think about it.