About the items:
I didn't tested this build, but i was thinking a lot about what items buy to play Urgot. Manamune and Archangel's Staff is a good combanation. Booth increases mana, as mana increases the Damage and Ability power increases too. So at 18 lvl you should have about 6700 mana, 2% goes to damage (134) and 3% goes to AP (201). Frozen Hearth will increase your mana too also will give you an ability cooldown and good armous, you will feel more tanky ;) Last whisper will help you killing tanks, thats very useful. The last item you can buy is trinity force, or somthing else, but you need moveing speed or mana, also bit of att speed.

About the spells:
*** you know you iff you want to kill somebody, you will have to chase them a lot so ghost and flash will help you chasing and surviving.

This build is for those who know how to play Urgot, how to use Abilities. This is just mine suggestion of items building. Try it, if it works write a comment also write what i need to change or ask me questions. OK peace ;)