Hello Mobafire and welcome to my Kog'Maw build,

Before posting OMG AP Kog'Maw sucks, read this:
This is an AP build, I know AS Kog'Maw is better than AP, but this build is for those who want to try AP Kog'Maw, it definiately does NOT suck.

Pros:
- Epic ultimate range
- Can finish off fleeing enemies
- Super slow
- Cheap manacost ultimate (if you don't use it rapidly)

Cons:
- Fast out of mana in teamfights
- Squishy
- Ultimate needs some good aiming
- Not very good 1 vs 1


How to play with him:

Early game:
Start with a mana sapphire crystal and 1 or 2 health potions, whatever you want. Don't use too much mana, try to use your void ooze on enemy heroes, hitting with this spell is easy. Try to stay as long as possible because you want your Rod of Ages fast! If you got it in 15 minutes you are doing very good. If you have it in 20 minutes you are also doing good, but if it takes longer than 20 minutes you are very slow. Don't forget to buy boots.

Mid game:
You should have the Rod of Ages and boots now. Because Kog'Maw is fast out of mana, a Tear of the Goddess for much mana. Because Kog'Maw is squishy and his ultimate is extremely strong (well, easier to hit..) in combination with slowers a Rylai's Crystal Scepter is a super item for him. One of the best items for him, you slow with your ulti on epic range and you got more hp. After this you can do 2 things. Epic AP or a very useful passive. Lich bane is very good with Kog'Maw because you do cast many spells so your basic attack will be boosted many times. For more AP you should buy Zhonya's Ring, just because it's epic.

Late game:
After you got a Lich Bane OR a Zhonya's Ring, upgrade your Tear of the Goddess to a Archangel's Staff before you fill up your last item spot.

Tips:
- Watch your mana because you are fast out of mana.
- Check bushes with your ultimate
- Void ooze in combination with your ultimate is very good, much more easy

Summoner skills:
I prefer ghost with Kog'Maw, if you want to finish off fleeing enemies, ghost and your ultimate are a good combination.
Flash for epic flee.

Thx for reading, bye,
HellPet