Oi. This is my usual AP Kog'maw build. IF you Got any questions then please leave a little comment.

For summoner spells i Use "Ignite" and "flash"
ignite beacouse then i can deal more dmg and mabye get kills on running people.
flash for a quick escape if youre gettin focused by enemy team.

If you guys wonder why i got so much attackspeed. Then it is beacouse With kogmaw's percentage dmg you will mabye need some more attackspeed. and the reason i have magic pen is for extra dmg on tanks.

My items. i Get a voidstaff early game for more burst with all the magic pen it gives. And sorcer's shoes for complete magic pen, that makes no tank safe!

I get morello's Beacouse It gives fine AP and some Cooldown reduction

rabbadons yea everyone gets that one. it gives tons of AP

Will of the ancients I get so i can stay longer out of base without loosing Hp

Abyssal sceptre beacouse it makes enemy loose magic resist and it is a good item for AP carries. And it makes sure you get assists.

If you want more attackspeed for your percentage dmg can you also get the item called "nashors tooth" instead of abyssal sceptre.

The reason i Grab ignite and flash is beacouse ignite gives good dmg and flash grants a wuick escape.