EDIT: Tried a new build, and loved it a lot more. Items updated.

This is my first guide so please bear with me. Rumble, the Mechanized Menace is a huge asset to any match. He has the ability to lane with another hero, or go solo. One of the few character's I've played that have a great game all the way through. Early game he's a threat, and by late game he's very dominant. This guide is to hopefully shed some light on a different way to build Rumble.

I set up my runes to give Rumble a huge advantage early game. With the added magic penetration and ability power, your flamespitter will devastate your opponent. The runes are also helpful late game, for all around potent death.

It's good to have a balance of both offensive and defensive masteries. The defensive covers both magic and attack damage. Remember, Rumble is a melee caster, so it doesn't hurt to increase both attack and magic offense.

Start off with a Doran Shield, then boots. These can be judged based on who's in your lane or the overall opponent's team. For the sake of this guide, lets say you guys are at a huge advantage and you just wanted to work some extra damage in. Follow up with a Rylai's Crystal Sceptre. The slow here allows for maximum damage with your flamespitter. IMMEDIATELY work your way into a Hextech Gunblade. Once again, Rumble utilizes both melee and magic, so lets try and use items that abuse that factor. NOTE: Don't forget to activate the gunblade. The slow can give you a HUGE advantage in a team fight. Afterwards, I go for Sunfire Cape. You are going to spend a LOT of time next to your enemies, and having extra HP and Magic Damage help. After that, it's Void Staff. The magic penetration is GREAT. Also, don't for get the guinsoo's rageblade. Similar to Hextech, this beefs up Rumble in both of his damage types.

ALWAYS open with flamespitter. I've tried using electro harpoon early and it never does what you want it to. Rumble is a chaser, and flame wave has a decent reach. Follow up with the scrap shield in order to keep your heat above 50. Proceed with Electro-Harpoon then try and max out flamespitter as fast as possible. This will ensure you deal the maximum amount of damage as early as possible.

The Equalizer is a little different from any other targeting ability you've seen before. You get to select the beginning AND direction of the spell, doesn't need to come straight from you. USE AND ABUSE THIS! It can be used offensively, by placing it in a line where an enemy is running either from or to you. It can also be used defensively, placing the line blocking a trail when you are being ganked.

Remember, Rumble is a chaser. Don't be afraid to get that last hit in on that hero behind their tower while full hp. Shield up and gtfo asap. Results may vary.