Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Why did i choos these items?
First of all the boots:
The boots make it easy to chase down enemies who have been hit with your Noxian Corrosive Charge (E) by using Acide Hunter(Q).
The max cooldown reduction you can have in League of Legends is 40% so with Youmuu's ghost blade u get 15% cooldown reduction with other benifits like attack damage and crit chance. It also has has a great active to chase ennemies down to their death.
With Frozen Heart you get 25% cooldown reduction with other benifits like armor which is useful when you use your ultimate (Q) and you also gain 500 mana this is great for spamming your Acid Hunter(Q) skill and you last longer in combat.
Kinda obvious. You do more damage with normal attacks and Acid Hunter.
Why you dont need attack speed:
You dont need attack speed because Acid Hunter has a very low cooldown, with these items 1.2 seconds and combined with your standard attack you have a nice attack speed.
Clarity is a must for obvious reasons.
What goes good with Urgot's ultimate is Flash because when you have done your ultimate you can flash back to evade enemies.
Exhaust is good foor chasing down ennemies.
It depends on your ennemies. ^^
Combine your Acide Hunter skill with your standard attack.
Don't feel shy to start a team fight with your ultimate but be careful!
More info comming made this in a hurry so stay tuned for more!