The runes you'll need will consist of mainly magic pen and magic damage. You should go with 3 mpen quints ap marks, then whatever you like for seals and glyphs those don't matter as much. All of these will boost your shroom damage, which is the only thing that matters anwyway

Just put 30 into offense, unless you a ***** *****.

The items you will need are morellonomicon, athene's unholy grail, void staff, deathcap, and liandry's tormnet. You can build them in whatever order, as long as you get morello's and athene's first. For boots just get whatever the hell you want, your w will move you fast, I reccomend sorcerer's shoes though. I hope you have fun causing people to want to kill themselves!