AP Kog'Maw
Hey people, I've been having so much fun with ap kog lately that I feel I should share the build I like and I am open to learning more tips on playing him from those of you with more experience.
Masteries: 21-0-9 (Take the AP path) Runes: I'm not on my pc to give exact details, but I take my standard ap mid lane rune page.
As for itemisation, Start
or
then rush
On my next back, it really depends on how my lane is going.
is good when you are just hanging in against a tough enemy but if I'm bullying my enemy, I like
or
before finishing
. Also dont forget to build
in the middle of all that.
By the time those items are built, I just go with how I'm feeling in the game I'm playing. These are a few of the other items that fit AP kog imo.
and last of aaallll 
I do NOT recommend
unless you already have a few kills and havn't died more than once. I had it fully stacked last night and could kill enemy tf with one E-R combo.
Just to wrap up, some gameplay tips that work for me. I'm not calling myself an amazing AP Kog player but my kda with it has been great. So I take w-e-q in the first three levels but ultimately max them in the order of e-q-w-r. I take w at level one to preserve mana in the early game. Not going to lie, you don't do very much damage until level 6 when you can constantly harass the enemy with your ult so play as passive as possible until then.
Positioning is key with kog'maw, he is very immobile and can deal damage from a good range so take advantage of his range but respect the lack of mobility. Last thing is to be smart with your ult. If you are in lane, cast it once then wait for the cost to come back down to 40. Landing the slow also makes landing your ult easier so his easiest combo is e-r or e-r-r. Don't go out of your way to land q because it would mean you are most likely in an unsafe position.
Hope that helps get some people into AP Kog'Maw! I'm no pro but it's too fun not to tell people about!
Oh yeah, spam the shit out of your ult in teamfights.