>>120371954Um, he has naturally high base damage on his abilities so you wanna run Armor pen reds, AD quints, health yellows and scaling MR blues. 21/9 masteries. Make sure you have dangerous game or I will find you and unplug your computer.
Longsword 3 pot for start, generally on your first back you should be getting enough for brutalizer then you want to go into a cutlass, and then just head straight for last whisper. Your early game pen with runes/LW/Brutalizer makes your abilities do an insane amount of damage, finish BOTRK and ghostblade after LW then go Bloodthirster into probably merc scimitar or GA. Build path is up to you at that point, but I generally go BT after LW/Botrk/Ghostblade.
Whenever initiating for a kill or something, try to save your W shadow unless you know no one else is around or you can kill without the extra damage from the 3rd shadow q, because generally a lot of the time you're going to need your W for an escape after you TP back to your shadow, or another gapcloser after you ult and they flash away from it.
Other then that, your laning phase is pretty easy and you shouldn't have to worry about missing a lot of CS considering your passive is an execute and your E makes it incredibly hard to miss CS as well. Your W>E>Q combo takes up your entire energy pool so be careful of that, when they're below 50-40% in laning phase, generally your combo 2 autos and ignite/the execute passive will kill someone without barrier, sometimes you'll kill even through heal or they'll be too slow to react.
Hope this helps.