If the game doesn't look like it's going to be long enough, or you aren't getting too squished, you can skip Banshee's and go straight for Eleisa's for the straight mp5/hp5. Also, Randuin's is just a bonus item if the game goes long enough. If you never get to it don't worry about it, same thing with Manamune. As for runes, it's kind of a personal preference. I would say mana/mp5 and attack damage though. It makes you hit a little bit harder than AP runes would, and gives you a little more mana to play with. The masteries plus items should put you at 40% CDR, which is cap. Have fun spamming! =D