I test Kog'Maw with dmg/atk speed and armor penetration. And if you play this build right than you are really good.
At the beginning you will learnto slow the enemys. You don't skill it hihger at the beginning because it cost a lot of mana. Than you make higher at the end higher.
After that you need to maxfor longer range and more damage. You learn it on lvl 2, 3, 5, 7 and 9.
You learn it on lvl 4, 8, 10, 12 and 13. For armor penetration.
Learn it every time if you can learn it. At lvl 6, 11 and 16. It make a nice damage if the enemy have not so much magic resistance.
And at the end you can makehigher. You learn it at lvl 1, 14, 15, 17 and 18.
Buyat first. You run faster and you have more attack speed.
Second you buy. You have more armor and attack with it. And you make 4% damage of the enemy targets hp. (Good with the skill Bio-Arcane Barrage)
At the third you buyfor attack speed, crit chance, dodge chance and movement speed.
Fourth you buyfor damage and life steal.
Fifth you buy. With it you have again more armor penetration and more damage.
At the last you buyfor more hp, a little bit damage more and for slowing the enemy.
SUMMONER SPELLS:andare good at the beginning to kill enemy champions because you slow them and ignite them for damage. And the advantage is that you are ranged you can attack him when he is exhaust and ignite and you can use the skillat the beginning.