This is a guide for an Urgot that can take some hits and really deal out the damage early game and will have insane damage output mid-late game. I have turned around several seemingly hopeless games with this Urgot build and although it might not be the best, it's what works for me at this point in time. Do note that this is just a guideline and you should always adapt your build to your enemies. But with Urgot you don't need to make many if any tweaks if using this build.

Hope you have fun, and take it easy on the Kill Stealing.

The first set of items before the Oracle's Elixer is for AD Urgot and the second set after the Oracle's Elixer is for Off-Tanky Urgot.

The Meki Pendant is a no-brainer with the cooldown on Urgot's Q Acid Hunter. Getting the Meki Pendant also leaves you with enough gold for 2 Health Potion, which becomes very handy for continuous early game harassing.

As soon as you can you want to get the Tear of the Goddess so that you can start spamming your Q Acid Hunter even more. Once you have obtained the Tear of the Goddess, you can and should spam Q Acid Hunter up to twice every 6 seconds (obviously if you're going for the kill then you should go all out, but otherwise, you should try to conserve your mana as you can still quickly run out).

After getting some Boots and a Vampiric Scepter, grab all the cooldowns you could ever want by finishing of your boots into the Ionian Boots of Lucidity and getting The Brutalizer. I get the cooldowns early, because they help so much for getting those kills that would have just barely gotten away if you didn't have the cooldowns... and there tend to be a lot of those when playing as Urgot.

Now it's starting to approach Mid-Game and you definitely want to get some power under your belt by finishing the Manamune. At this point it will start to become cost effective and will keep gaining you AD to carry you through Mid-Game until you've gotten your Guardian Angel, which happens to be what you get next. Urgot with a Guardian Angel is a complete build in itself it's so amazing, but why stop there... we NEeds MOoRe POOWWWERR!
If you so desire you can get Bloodthirster Before the Guardian Angel if you really want that power, but I usually would get it after just because you can already dish out decent damage and the Guardian Angel makes you way more survivable.

This is the moment you've been waiting for, the complete build. Once you have procured the last item Black Cleaver. Your opponents will simply give up upon you exiting your base and promptly surrender out of fear of having terrible nightmares involving Urgot, unless you're building the off-tanky version, in which case they will still cringe in fear but not give up because they are too naive to realize the devastating power of off-tanky Urgot.
If you still haven't beaten them for some reason after this, just sell The Brutalizer for and Infinity Edge.

Just remember that you're Q Acid Hunter doesn't apply the effects of Black Cleaver. Yes, this means you have to actually walk up within range and hit them with your basic attack. I know life is so difficult, but it is what it is.

Urgot's Q Acid Hunter:
Get this skill first. Max this skill first.
This is Urgot's bread and butter. You will come to love this skill and your enemies will hate it. This skill is a skill shot, so you can hit anything anywhere with it. When you use Urgot's E Corrosive Charge, all you have to do is hover your mouse over the poisoned enemy and press 'Q' and it will shoot them with the missile. The really cool thing is that if an enemy is poisoned, and they go into the fog of war, if you can guess where they are with your cursor even though you can't see them, this skill will still lock onto them. You will kill countless enemies while they are BEHIND their turret without even so much as getting a scratch because of the crazy range on this. The range is basically to the edge of your vision, although if you mess around with it you'll find it comes just short of the fog of war.

Urgot's W Terror Capacitor:
Get this skill third. Max this skill second.
This skill pulls a double duty: providing you that shield at crucial times and while the shield is on makes your Q Acid Hunter slow the enemy. Really, what more could we ask for.

Urgot's E Corrosive Charge:
Get this skill second. Max this skill last.
This skill is the key part of Urgot's combo. You can use this for farming creeps once you've got enough mana too. But the main reason is for giving your Q Acid Hunter that devastating lock on. Your other skills are better to max first, you only really want this for the lock on, so just get one point in it to start.

Urgot's Ultimate Hyper-Kinetic Position Reverse Hyper-Kinetic Position Reverse:
This skill is at this point my favorite ultimate in the game. It only takes a little bit of playing to figure out when to use it well, and a little longer to figure out when to use it amazingly. It freaking stuns the enemy, and switches your places, then slows them down! There are so many uses for this skill from picking up a kill, to initiating a fight, to saving a teammate and then picking up a kill...

Once you've got your lifesteal and your Guardian Angel, Urgot is primed and ready for a team fight.

Urgot has the power to turn a game if you know how to play him right. With Urgot's passive Zaun-Touched Bolt Augmenter, you want to take out the carries, not only because you can kill them quickly and that's who you should be going after anyways, but because you will also decrease the other team's main damage output at the same time because of the passive Zaun-Touched Bolt Touched Bolt Augmentersize. If you've got a really coordinated team you could even auto attack one damage dealer with your auto attack while hitting another nonstop with your Q Acid Hunter.

Once you've got the Guardian Angel you can initiate the fights with your Ultimate Hyper-Kinetic Position Reverse Ulitmate Hyper-Kinetic Position Reverse. You want to target either someone completely out of place, or swap yourself for one of the carries so that you teleport their carry right into the center of your team while one of their main damage dealers (that carry you are so conveniently Ulting) is unable to do anything. It is wise to target the AP carry first if you are initiating, because with this build Urgot's Magic Resist is considerably less than his armor.

His Ultimate Hyper-Kinetic Position Reverse Ulitmate Hyper-Kinetic Position Reverse will even do the job of eliminating that pesky tank that thinks he's so hot if he gets out of place just a bit too far away from the rest of his team...or too close to a turret.

To summarize how to teamfight:
You pretty much want to focus the carries unless pre-fight someone gets out of place in which case you should do them a service and transfer that shiny blue buff they're wearing over to someone on your team.

If your team is nice enough to give you Blue Buff then you can happily cast skills endlessly to your hearts desire and kill anything that enters your line of vision.

If you're comfortable initiating you can do it well with this Urgot build, just know that you are not a true tank. If you are not comfortable initiating then your Ultimate is just as well used to trap those pesky enemies who try to leave the team fight party before your team gets that Ace.

I take Teleport and Flash because being an it simply lets you stay with it when stuff's moving around, or get right back if you happen to die... if. Flash is amazing with Urgot, letting you pick up those kills with ease or escaping when needed.

Early game it's easy to get last hits since you're ranged, and once you get to mid and late game you can push like crazy since you have an aoe poison, a heavy hitting basic attack, and a heavy hitting Q.