Hello, rumble is a very good support character if you can learn to play him right this little yordle can be a teams best friend. I will be updating this character as I become more familiar with him just thought I'd share a build thats been working well for me. Also if you have any advice I'd love to see the comments please be constructive.

Ahh runes what more is there to say, I go for health regen per level quints, dodge seals, magic pen marks, and magic resist per level glyphs. I feel these are the best because its always nice for a melee character to have survivability early game and being the early pusher that he is ever bit helps. You can also use ability power quints or armor seals if you want work well also.

Tank masteries are easily the best for Rumble because he uses no mana and altho has decent melee damage is mostly an ability power champion. You can shuffle some masteries around so you can take less damage from minions or deal more to them to farm better which is a good idea. but I'd suggest not going further than Knowledge in the offense because theres not much past it that is of any use to Rumble.

My 2 favorite are ghost and ignite because speed and a dot are always useful. Others that will work well are flash to get in closer with flamespitter, cleans to remove crowd control attacks, or teleport to save a tower or ally.

This char is well built for harassing but is best for team fights, because his shield and flamethrower have 5 second cooldowns he can run into fight and chase down most any character and then his ult is perfect to either slow opponents from escaping or helping your team escape (but most of the time you are able to lure into bush and keep them on the fire line it creates).
Also he is a good baiter because of his scrapshield speed boost.

pros
great push beginning game
great team fighter
does good dmg throughout game (does less dmg if tanky build buit still good as far as tanks go in my opinion)
good escape when needed by team mates

cons
a bit squishy (unless you use tanky build)
not full mage so cant instant shut down

Havent tried but if this character can jungle plz tell me cuz id love to try that XD.

Ok beginning game I just keep flamespitter up as much as I can and people just tend to stay away and this works even better with a ranged char at ur side (ashe or fiddles are my favorite combo)altho any character with a stun or slow is great because any enemy will be to scared to try to push you. Which in my case has led me get many double kills before the minions even spawn.

Always keep ur heat around 50 at all times can be done at first level by spamming flamethrower (always get this skill first no exceptions) and only over heat when you are going for kill. My skill use goes as follows, I pop my flamespitter then run in with scrapshield then I send the equalizer behind them and use my epic slow over heating then slowing the char again and pounding them till there 6 feet under (note if you have 55 heat you can use all 4 abilites overheating on the fourth). His ult is a new kind of skillshot so it'll take some time to get the hang of (ohh and just so you know after you've left clicked to set path if you right click before you let go of the left button it will cancel the carpetbomb).

Firecape stacks well with flamespitter so very aware of that as it will help you, and don't worry about cooldown items becuse his spells can be spammed as much as you want as long as you keep an eye on ur heat.

The hextec revolver is great but sense he doesn't really do much physical damage the gunblade isn't recomended but does still help a bit its just not very practicle. But the revolver isnt really needed just nice survival.

And i know that lich bane has mana but all of its other abilites are amazing for him with more speed, MR, and its passive helps a lot in fights.

Also try the rageblade if they dont have to much magic pen just swich with void staff.

As far as farming foes if you are looking to kill as many minions as you can the get the damage to minions mastery and keep your flamespitter up at all times and its pretty much as easy as that.

And for farming people have a character with stun or slow run in and stun then chase down with flamespitter and scrapshield. And just as a note it is really easy to get a double kill before minions spawn as Rumble if you have the Danger Zone and flamespitter. But i would recomend not turretdiving at level 1 :P try to let them get to the bush closest to your turret use ghost to get close use flamespitter and ignite one of them. I find they tend to drop pretty quick after that if done right (made even easier when you have any ally next to you).
I've been able to solo double kill a sion and ash team out of range of both turrets and get to level 2 before minions even spawn so i know it can be done :P.

In conclusion this char can go more damage build or more tanky. It all depends on how you want to play. He can spam all his non ult abilities as much as he wants so long as you keep aware of your heat, and rumble can turret dive like a champ if your smart. He best as a team player though and his ult really is what is says I hope this has helped you and have fun. And early game he can dominate.