This is how i play Rumble. It usually gets me alot of kills. I think of myself as a glass cannon, u gotta go all out and really commit to the fights if you want to win. fyi all my discriptions are in laymans terms becasue im too lazy to figure out the offical names. use your brain, im sure you'll understand.
Start off with Rank-1 Shoe and 3 hp pots. Then get the mats for the AP Deathcap, or finish your shoe as a magic pen shoe if you need the extra run speed early on. Once you complete your Hat, you pretty much are ownin, so you can either get the Magic Life Steal Book Thing that gives aura to your teammates, or if you want to spend more money and get some hp get the Slow Staff. If the enemy team has alot of AP people, go with the suggested AP/MR/-theirMR Staff. Usually at this point the game is over and we win by a landslide so i always mess around with my items. I dont know how Magic Pen works with the 40% Magic Pen Staff and my +20 Magic Pen Shoes and my Runes and Talent Tree stuff, so it might be overkill but i usually get that 40% Staff towards the end. Also i get a second hat cause im all about stacking the AP for even more pwnage.
As for the Runes i use Red: Magic Pen Yellow: Dodge Blue: Flat AP and Quit: Flat AP
And for my Talent tree i spec 9/21/0. You're prolly wondering why i go def instead of Atk tree. Well its mostly cause i want that extra hp in the start, and that run boost from dodging cause i couldnt think of a better yellow rune, but most importantly its for the bonus AP and Atk Speed modifier. It works well with the AP Hat. Also make sure in Atk tree to get the scaling AP, and the Magic Pen. If you dont, yer dumb.
Skill wize, i lv up Q (fire) then E (pokey stick) and lastly W (zoomshield). Dont mess this up or you'll cry, trust me i've done it. Q, E, Q, W (dont forget this at lv 4!) Q R (ult ftw!) uh i forgot where i was but u get the picture.
So remember be brave young Yordle, you may die, but you'll kill something! isnt that great! Also make sure someone else initiates cause stuns and nukes make u = DEAD. Then run in, light em up, poke their bums, and watch em stand in your ult like idiots!
One more thing! For your ult (R if you've forgotten) dont listen to idiots who say initiate with it, if u do they'll walk outta it. save it for when the fights commited and they dont want to walk outta it cause they really want to kill your partner. or use it on someone running away, just make sure you aim it real good k. lateroids future Rumbles! make me proud!