Not Updated For Current Season
Welcome to my Rumble makin' you grumble guide, why is he supposidly makin' everyone grumble... because he will rockem' n sockem' and he rides around on a giant robot... what could be better? Oh how about the fact that all his moves are on rediculasly low CDs!? Playing with fire doesn't quite cover the fun you're going to have with this beast of a rodent! Enjoy
I go with a specific burst of magic pen and ability power, you may want to change it up with some reenforced magic pen ruins so you don't get focused and blazed in ranked matches, but for rumble starters you're going to want all the magic pen and AP you can scrounge up. Another way you could roll is armor / health but again about preference.
You want to max out your flamespitter for constant pre and early game harassment along with your harpoons for another constant harasser, while having one point in your junk-shield for little punks like ezreal or teemo. You are going to want to get your points in your ult every chance you get because it is very important for team fights and to escape from nearly any gank due to incredible mid/late game damage output.
Somewhat squishy with a strict burst attitude. I start with Dorans shield to get a little health and regen because of the fact that you run on HEAT! No mana problems for this new kid on the block.. and enevitably no problems at all. I get the magic resist and 30% off CC boots because rumble gets focused by stuns/snares/etc first due to his crazy output of damage. Ralai's is very important early game and if you get fed, trust me you will get the Ralai slow and you will gank like a super-pro. Constant skill shot harpoons and flamespitter slow.. Along side your ult can send anyone to their base with another rez timer. Zhonyas is very important down the line along with magic pen... If the other team is somewhat braindead and has no magic resist you can switch it up for another Rabadins or maybe a tank item or survivability like Banshees.