it's funny. cause in that game i FRONTDOORED THEM O_O

I meant your item build, lol. Thanks though, didn't know some of that, mostly about positioning. I'd figure you could build ridiculously squishy and have kog stand really far away to nuke the shit out of them.

Also, isn't w just an auto attack buff? I don't see why you'd be auto attacking at all late game.

Your Q has a little over 6 second cd with little cd reduction, your slow has closer to 9 or 10. Spamming your ult drains you of mana pretty damn quick, so you have to spread out its use to save for either immediate emergencies (somebody getting too close), or when range is crucial (i.e. beginning of fight, poking, or end fight cleanup). Plus 13% of max health per hit isn't that bad to toss in here and there. Against squishies, your ult, slow, and q should hit for more than that %, but your W will hit harder on beefier targets. This allows kog to spread out his focus for effective damage on both the bruisers/tanks and the squishies, or use all of it combined for single target rape.

W's length also makes it serve as a good in between for when your Q and E are on cd. It should last for about the same length as your E's cd, so it's basically extra damage to supplement yourself while you wait for it to come off cd. By this time, most team fights should be over, but then it gives you some much desired cc for either chase or retreat, depending on how the fight went. Assuming the teamfight wasn't a total rout against your team, Kog can defend the base incredibly well by himself, considering he should leave most teamfights relatively unscathed because of his range. (I've done 3v1 defenses with kog consistently. Each time was a triple kill. Even a couple 4v1s which normally resulted in a 4 for 1 exchange.)

In addition, W's range is a good approximation for the ideal range kog maw should be in for most team fights, as it maximizes his damage potential, and gives him a buffer range to initiate a chase for cleanup when the teamfight ends, or to pick off an early retreater. Basically, it should put kog's ult range (at level 16) one or two of your ult's aoe further out than the enemy ad range when the fight starts. This allows you to put pressure on the ad range when they decide to move in to start their damage. Not only does this put a ton of pressure on the ad carry to stay mobile, thus reducing their total damage output, but it also gives the chance to take the ad carry out of the fight before they even deal damage. If the area where the fight is taking place is cramped, your E can further disrupt the ad carry's damage by keeping them out of range of important targets longer, namely you and your own ad carry. It also makes him/her a sitting duck for your ult (it's pretty hard to miss a 40-something% slow that lasts for like 3 or 4 seconds, higher if you have rylais and hit them with it.)

Basically, why avoid using potential damage when the range on it makes risk negligible by itself, let alone when you have 3k health and 2 summoners to bail yourself out.

I had to jungle.... So I picked Karthus. Because I don't have Maokai.

rofl maokai jungle. Fun, but that instantly disappears if the enemy team tryhards whatsoever and counterjungles you.

We were playing against premades, so I didn't think it was likely.

and we won after

Kog'Maw is good Hero, Range DPS or AP

Yeah it looks like a pretty sweet build.

Although did you get your Rod AFTER Zonhyas? I generally like to get my Rod by about 20 minutes otherwise the passive is either not charged for the first few team fights or ends up not charged at all if the game doesn't go on past about 30 minutes.

I would also consider getting Rylais a bit earlier unless the team is building a good bit of MR.
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Maoki jungle's great, though yeah, getting countered as him fucks up everything, especially when he starts at wraiths then to Wolves leaving Blue and Red up for steal in a jungle that's already unsafe for his first clear.
On the other hand he's my favourite jungler due to his amazing ganks with Twisted Advance and his knock back.

Eh, Maokai is too easy to bully. I wouldn't pick him in an arranged five unless I saw the other team had a passive jungler like Amumu, Cho'gath, Rammus, Fiddlesticks, and so on.