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.
While this build is a power house of damage, it will not make you invincible. This build relies heavily on your ability to get and keep the stacks on your Sword of Occult and Mejai's Soulstealer. If you do not feel like you will be able to reach 10-15 stacks and keep them, do not use this build. Also, if you do not have good map awareness, do not use this build. Like I said, the object is to keep the stacks you get. Limited map awareness is severely detrimental to this build's success.
Demand mid. Most players will question this request, but demand it all the same. Most of the time you can claim mid by suggesting the stipulation that you'll give up mid once you hit level 6. Most people will either forget about this or be so wrapped up in their own lane that they'll forget you said it. You will, every now and again, encounter someone who does remember. Give up mid and start ganking the lanes.
Your objective is to out-level their entire team. This means killing their midding champ as soon as you can. However, do not attempt kills needlessly. If they fall back to their tower, do not chase them unless you are 100% sure you can get away alive.
Start out with a Long Sword and a Health Pot. Last hit creeps with melee attacks and Mark. Try to make your first trip back when you have enough for your Boots of Mobility. I know you're asking yourself, "Why boots first?". The answer is simple. You need to be able to move quickly to avoid and set up ganks. You should start attempting ganks around level 8. Though, try to avoid initiating ganks if you any less than 3 Shadow Dance charges. If everything is done correctly, you should have a 2-3 level advantage over your enemies.
Continue to gank. During team fights, focus on any ranged champs the other team may have. If there are no ranged to be had, focus the champ with the lowest current health. Yes, this means attacking champs with full health, but less than the tanking champ that's at half health. This does require good awareness however and takes practice to get right.
If everything goes your way, their team should be surrendering at this point. You should easily be in the double digits with your item's stacks and have caused enough havoc that the other team runs at the sight of you with a 3v1 advantage.
This build relies heavily on your ability to survive. And as your masteries and items are Offense, you will need to supply that survivability.
Rate and Comment please. If you have any questions, please feel free to ask.
Note - The Seals of vitality are placeholders as Moba has yet to add the Energy/5 runes. I use Seals of Meditation x8.