Hey! I'm Jotinhabr17 I've starting to play Rumble about a good Week ago or so, i have noticed that he has some great potencial for high and low elo ranked games.
So Rumble Q Flamespitter Is a very, and i say very good skill, it has a good area of range constant damage and a realy high duration.
Rumble W Scrap Shield Is'nt a godly skill but can save you alot of health (use while chasing a enemy Bc it gives extra MS)
Rumble E Electro-Harpoon Is pretty decent it has nice range and later in the game good damage
Rumble R The Equalizer Is a awsome and very powerfull ult it has a good range Does constant damage and slows enemys in the area

Liandry's Torment Extra health and damage at early game + magic pen
Sorcerer's shoes MS and magic pen
Spirit Visage Against AP this item is godly health regen and health + the magic resist is realy OP
Dead Man's Plate Agaisnt AD You can have Nice armor and health for the cost of the item I'd say it is worth it
Rylai's Crystal Scepter Your Q will not be stopped
Zhonya's Hourglass good against AP and AD champs,
but dont forget to use it
Rabadon's Deathcap This will give you All the ap you need It's passive is massive
Dead Man's Plate is good against AD champs like Yasuo or Riven

Pros
+Easy to get CS
+Very strong poke with Q After first item
+Good in both early and late games

Cons
-Not that tanky
-Passive can ruin your kills
-No good escapes

Rumble farming skills are pretty good and heres a quick guide on how to farm With Rumble

Using Your Q Flamespitter Is what makes it easy for you to farm just use it when minions are below 70% HP and your garanteed all farms just dont use it when minions are full on HP! Using your E Electro-Harpoon Is also amazing for last hiting because of its Cooldown time

So you want some tips for Rumble ? Well here you go!
- When you make your first tank item and its ready to be used go strait onto a team fight, if you have flash or maybe your W go ham and run into The enemy, don't forget to tell your team to follow you. also ult, try hit all them 5 enemies or 4 or maybe even 3 just ult! Spam your Q win TF, win game
- I use this one alot, chase enemys down with W and Q activated W is good for your bonus MS and Q you know what for :)
- Always take a small look at your passive! don't chase enemies When its over 90 or you cant use your Q Just W and E
-Always try to fight in small places, so enemies dont have many places to go to when trying to escape, try to ULT when the fight begins

- Illaoi] Stay safe, wait for ganks or try to poke her with your Q and E
- Tryndamere] There is nothing you can do. wait for ganks
- Darius] He must be banned!
- Fiora] wait for ganks, or just try poking her, but stay under your tower

If you are going against a ranged champ i would recommend you stay in bush before getting into a fight with him, get level 6, stay in a bush and when he comes near the bush you're in, use your E to slow him, activate your W, use your Q and ULT when needded.

Against melee champs. Just poke then with your E and Q as much as you can, if possible ask for ganks. At level 6 try to fight him as much as you can, if he engages on you, ult on him and use everything you have.

Against ranged magic based champs. Just farm and if they engage you,
flash on them, use your W Q and E. ULT if needed. Rumble is weaker against these kind of chamions, try staying safe and asking for ganks