tried this build out with some great success, new to playing rumble but it worked out great. I'll be trying other builds but +1 to your guide and added to my favorites for sure!

i really liked your build but i just start with maxing E first. personally.

Completely agreed Dmarco.

Most of the points made in this guide conflict with each other and seem bad overall.

You say you don't take defensive masteries because you're not playing tank Rumble - so what? Defensive masteries are key to winning your lane as you are vulnerable to harass, and the more migitation you have early on allows you to be the bully that Rumble is in lane. You say "if you play against someone with a strong early lane presence, like caitlyn, take harpoon first" - this is a bad idea.

You always want to take flamespitter first. Early teamfight? Flamespitter. Someone with <600 HP in lane level 1? Flamespitter. Flamespitter allows you to dominate your lane from the start, and does more damage overall than harpoon does overall while causing a bigger threat. Your skilling order is terrible, to put it nicely.

I just do not agree with your runes. Flat Health Seals? Flat CDR Glyphs and Quints? Movespeed Quints, Health Level Seals / Flat Armor Seals and Flat Magic Resist glyphs allow you to bully your lane with no risk - especially with defensive masteries.

You rush Rabadons and take CDR boots first... You need early rylais so your ultimate forces people to actually use flash if caught in it, otherwise they can walk out and take minimal damage, even if positioned really well. If you're using it to finish, the longer they are in it, the higher chance you have of actually killing them. Rylai's also makes all your other spells amazing while giving you the needed health boost. CDR Boots should be replaced with Merc Treads or Sorcerers Shoes, but most likely the first option.

Now here is where your build conflicts - you say you are AP and not a tank but you insist on replacing WotA for force of nature if needed - why not get both? Hextech Revolver is a core item on Rumble.

I don't understand your emphasis on obtaining 40% CDR - CDR is worthless, the more you spam your skills the more likely you'll reach overheat. With 0 CDR it's already very easy to upkeep danger zone, even at level 1 you can stay in danger zone with flamespitter. The only real justification is for having your ultimate up more often, but is it really worth gimping your build and champion as a whole just for that extra benefit? There's so much rumble can do outside of his ultimate with a proper build but with very poor defensive stats you've restricted the potential to just "Use ultimate then use skills."

You've basically, with this build, made Rumble less of a one man army and more of a team fighter. He excels at being individual and he should be able to be so aggressive in teamfights he can walk all over the enemy team. You won't be able to do this until you're fully itemized, but that doesn't matter if you wasted all of his early game potential with this build.

-1, Sorry.

I have really found that when facing a morde, rumble is better until level 6, his shield is more OP becuase with double electro harpoon unless the morde is a total badass, hes gonna turn around and try to run (even though he is gimping), and his shield usually gets owned by double harpoon then about a second of flamespitter. Your shield is really better than his as it can be activated any time and when morde is trying to survive low level, keeping up the shield is not gonna happen. And after 6 mordes ult is really useless because of scrap shield. Btw i crave electro harpoon first level it might as well be an exhaust, how can you not get first blood with it if your enemy is kind of dumb

Well Your guide seems good but i dont like your build. CDR is not needed at all for rumble, he has low cds and the benefit of having lower cds would be to keep your heat up but that isnt an issue without cdr runes. Another thing is that rumble is someone that your run up and face check people, not a squishy ap. Off-tank AP champs are usually OP and should be take advantage of for example, Vlad he use to be really strong but they nurfed his passive and abilities. Nunu is a tanky/support ap champ who is great. Mord can be played as a tank or ap-tank and bolth work great it just depends what ur situation is, but no one plays him as a squishy ap sucessfully. Just some thoughts hope you think about it

Great guide. I approve. I really like the electro-harpoon at level 1. Most people dont like this, but I farm really hard with electro-harpoon and have managed quite a few first bloods with it (more often than when I start flamespitter, especially after the nerf).

finally someone made a guide that is more towards AP. i have always played rumble extremely similar i can not find a single flaw in this guide.

it's nice

I'm confused as to the purpose of exhaust. Exhaust isn't crucial unless they have a heavy dps on their team, and as Rumble you wouldn't want to get close enough to an enemy to use exhaust as a buffer. If you can get into range for exhaust, you should be able to slow with harpoon or ult. Just a thought.