You want magic Penetration for your poison trail and fling.
Movement quintessence so you can stay away from their stuns and slows.
1 endurance quintessence because you get increased health also including the greater seal of endurance gives you a total of 6% increased health.

If you noticed all these items give you movement spd and also mana, thus increasing your chance of them not getting you and your chance of not running out of mana all in all it helps you with taking down champions who rush under tower with low hp. Don't sell your stone till u build trinity.Then later sell ur kage pick for lich bane.

Pros

Faster Movement Spd.
Lesser chance of being caught by enemy
champs if followed.
Can slow to inflict more damage.
can stop low health enemy champs from
leaving team fight.
thus allowing your team to earn kills.

Cons

Don't know much but if you try this build and find that it has some post some messages and tell me