Rumble is a great and fun player and has some powerful attacks.

Pros:
Excellent survivability
Able to launch two harpoons
His use of heating allows for tons of damage output
Fun for turret diving

Cons:
Overheating can become a problem
His speed increase from scrap shield lasts only 1 second
His ultimate is annoying to position.

I chose these runes because he needs the health when pushing towers, his armor is useful when melee or ranged are attacking you and you need that extra protection. Ability power for some extra damage output.

I take a 9-21-0 tree because I need the magic resistance penetration. For defense I take my usual build, grabbing the health and dodge for extra protection when you are harassing in the beginning.

I start off with a ruby crystal to Ruby crystal for some extra protection.
I will grab my phage because I like to slow my teammates.
Later I grab my boots so stuns don't kill you off.
By this time I am almost set but I will upgrade my phage to a frozen mallet, easier slows and when your in overheat, you will have some more damage.
Now I leave the rest to you, but I grab the hat for extra damage output.
Everything else should be understandable to buy, but I usually stop at the hat because that is the last of the game.

Beginning
I grab my crystal and head off to a lane, mostly top or bot, and bring mainly a support like Sona, or just some range like Annie. Use Flamespitter to farm up all the creeps, and try to use it as much as possible, when you get to 50-80 heat, try to conserve your Flamespitter so you will always have the extra damage, but not overheat and be a sitting duck. When you get Harpoon, your harassing days will start, try to launch a harpoon, then predict where the enemy will head. Remember that harpoons give off heat, so try to moderate when your using one or the other. Also note harpoon is a skill shot so you may even shoot through trees! When getting attacked, try to run away with scrap shield, but remember the fight won't be over, many times I can turn a fight around by running away with scrap shield then firing a harpoonx2 while heading back to a turret.
Mid
When you have your ultimate, you will now be able to successfully gank with ease. This ultimate is pretty simple but can be quite annoying to place, you have to click and hold where you want it. Now setting it in correct positions is easy, you can place it in a line so when the enemy is running away, they will have to get out and spend time moving over, allowing you to catch up, or take the full force, mostly resulting in a kill. This can also be placed as a wall in there escape route so they will be foreced to walk through it or run in a different direction.

This is one passive that your character has that will need a whole section to cover it.
Now your heating has a bar that goes to 100, most abilites cost 20 and you will learn how to coordinate them to ensure your full damage output.

0-50: During this point, you must build it quick as possible, easiest way is to start flamespitter, then cast a harpoon, put on shield, and then cast your next harpoon. This will bring you to 60 heat, then you will watch out.

50-95:At this point you should be cautious of overheating, learn to use abilites when needed, but try not to go under 50. Many times you can just farm with flame spitter by jumping flamespitter to 80 then let it fall down to 50-60, then pop it back up. When harassing with harpoons, plan ahead. I will wait till 50 heat then launch a harpoon then start flame, this will give me enough heat so I can still use my shield as a getaway, or a attacking ability. Remember Ultimate costs no heat, but don't worry about that.

100!: During this time your are overheated, during overheating your attacks will increase by a lot but you can't use abilities. I will mainly overheat after I use my first harpoon so I will still have my second Harpoon for slows. Overheating can be dangerous because you lose your shield ability. Overheating can be used for farming creeps when no one is around.

Rumble is a fun class with some unique ways to play from the rest of the heroes, you may not always get the kill, but you will sure make the enemies wonder why they couldn't kill you at 10% hp.

Thanks for reading and comment below!