I dont have to say much about runes.You can use the classic runes of mid(x9 magic pen,x9 armor,x9 magic resist,x3 ap quints).But,you can also take magic pen marks if you dont love hybrid.In my opinion hybrid certainly outscale the magic pen marks..as you lose some magic pen for a lot armor pen.Whatsmore,if you play against full ad team or ap top you can try to use scal. ap against mr which will be useless when u go gank....

[PROS]
1)Huge Oneshot potential on anyone(even tanks)with core items(DFG,Lich Bane)
2)Much outplay potential with Q and E
3)Constant invulnerability from E spam and clutch Zhonya use makes him very slippery in teamfights
4)He can easily take a kill on 3 and 6 level.

[CONS}
1)Easily Countered
2)Needs a lot of practise(even Pros can miss his ulti)
3)He's melee
4)Very easy to pop on teamfights