Ap kog maw is very powerfull APC that can do like Le Blanc throw it all to kill and if u can kill just keep firing with R and Kog Maw will feast 3:).

Runes are that are used by a lot of good players and they can secure a kill and a safe escape.

Masteries are simple they are 23-0-7 good for farming,mana regeneration,and doing a lot of damage in team figths.

Items that you use are general build and they can make you survive verry easily team figts and carry hard.

U need to first use AP Kog Maw vs Bots because u need to look how to kill u can no just use it like u already know just use my combo and leveling and it will be a secure kill and if u are counterd deff it and call more ofted your jungler.

Ignite and flash ; ignite to kill easyier and flash to run or catch up but more for running because R has a lot of range and a lot of magic damage.

Farming is harder with ap then ad kog mah but with some ad boost from masteries and leveling E farming will not be a problem .

U need to make a combo if you want to kill first you E then Q and at last just harrass with W and R.But be careful without any support from your team you will be killed easely.

On ranked games this items well you need to look first against who you are playing with if they are tanky then this and if they are more swift killer then try to swift them faster with attack speed.Try to ban elise,zed and tresh the most likely champs that will counter you and prevent to carry your team.

In team ap kog maw he is the one that like ad kog maw stays in the back and he uses his combo and does a lot of damage if u are focused then just figth and use everything items , spells, summoner spells and passive to kill.Try to positioning your self betwean adc and engagers because u need to move to kill and try to be not caught by enemy tanks and assasins.