Hi there this is my first build and i mainly made it to see what people think of it.

My whole build is based around helping fiddle get fed so that he can dominate mid/late game.

Greater Mark of Insight: This is to help get in more damage to get those early kills.

Greater Seal of Replenishment: This is to help with that early game mana loss on Draining targets.

Greater Glyph of Focus: This is so that you can get more spells off in a shorter time.

Greater Quintessence of Revival: I really don't know what else to put in there and this seemed useful late game.

The Masteries I've chosen on the offensive side are there to help reduce cooldowns and increase magic penetration.

The Masteries I've chosen on the utility side are there to help mana regen, buff time increase, more cooldown reductions and some speed.

Mejai's Soulstealer: I like to get this item early as when you get those early ganks it starts to really help increase your damage helping you get more kills.

Elixir of Brilliance: I have that in there to help boost my ability power and really reduce my cooldowns.

Rabadon's Deathcap: Lots and lots more ap for that super life drain.

Zhonya's Hourglass: More ap and will help if you jump in and they try to focus you down.

The Skill Sequence iv used here gets Drain and Terrify up very quickly.
This allows you to fear your opponents and drain while they run around like headless chickens.
Against a single opponent you should be able to drain them to death in no time.

I use Flash and Teleport.
I use Flash when i ulti from behind bushes or from behind my tower. It also helps to catch anyone that runs away or to escape the narrow clutches of death.

I use Teleport to harrass around the map and to help save my allies. Or to help get those kills.

PROS

• Great 1 v 1 character for all of the game.
• The very low cooldowns will help you keep drain on permanently.
• Crowstorm is great for causing commotion and distracting the players and brilliant cleanup.
• Great in lanes. Can outlast many opponents.
• Great Surprise ganker. Covers the distance to any hero and keeps them there.
• Can tank dragon really early and can tank baron at level 12 - 13 with blue buff.
• Amazing crowd control for getting away, saving a champions life or killing a champion!

CONS

• Not alot of mana so sometimes you have to be careful how your spending it. Get blue buff!!!
• Crowstorm takes awhile to charge so you have to make sure your out of sight when you start casting.
• Crowstorm can put you right in the middle of a team fight. Sometimes that costs you your life.
• Sometimes slow at jungling.
• Not a good farmer! Dark Wind only hits 5 targets and using Crowstorm to farm is overkill. Need to be good at last hitting!

You should focus on getting the last hit in on most creeps and also focus on getting the blue buff and the dragon when ever they are up because you can and blue buff really really helps this build.

I suggest you use the fear on opponents that are doing the most damage to your teammates and then draining those to death. Most of the time you will be at the back throwing in Darkwind till your ultimate is ready and then you jump into the middle of everything.

In summary this is an awesome build that I've used.
Any helpful suggestions and constructive criticism would be welcome.