This is my rumble guide I have seen many rumble's and most die easily or do little damage. My guide will show you how to build a strong off tank ap rumble. Rumble is not a strong tank because he has little cc and not a great pure caster because of how he is very melee based. Combine these though and he is a unstoppable force.

Pros-
*Hard to kill unless focuses
*Strong Dot and burst
*Not reliant on mana
*Overheat gives autos magic damage based on ap
*Danger zone increases damage
*A weak shield that blocks true damage
*Dominate lane
*Gets a kill at 6 90% of time

Cons-
*Melee and short range spells except for R
*No hard cc and little soft cc till rylias
*Overheats quickly
*Easy to focus
*With runes and masteries you start with 666 health 0.0

Junkyard Titan

Rumble's abilities don't cost anything but generate 20 heat. When Rumble reaches 50 heat, he is in the "Danger Zone", causing all his basic spells to have additional effects. When Rumble reaches 100 heat he overheats, silencing himself for 6 seconds to cooldown completely and causing his physical attacks to deal an additional 20 + (5 x level) + (0.35 per ability power) magic damage for the duration. While not overheated, after 4 seconds of not using his basic abilities he will start losing heat at a rate of 5 every half second, and 2.5 seconds later at a rate of 10 every half second.

A great and horrible passive at the same time. If used correctly you can over heat to do massive damage after a strong combo. Using level 1 w spam will also always keep your heat the same. But if you incorrectly you can silence yourself easily and fail to get a kill.

Flamespitter

Rumble begins torching the area in front of him with his flamethrower, dealing 30 / 60 / 90 / 120 / 150 (+45% of ability power) magic damage per second to all units in a cone in front of him for 3 seconds. He can move, attack and use other abilities while the flamethrower is on.

While in the "Danger Zone", this spell deals 30% additional damage.

His most powerful spell once you have started to build ability power because of its short cool down and AoE and DoT. Chasing with W+Q means that while not in melee range you can keep up or out speed while doing a ton of damage. Once our E is finally up you can use it and get into melee range W+Q again over heat and pick the enemy off IF chasing. Level E over Q results in more burst but leaves you completely vulnerable because you can not over heat at all and it has a long cd. I level this at 1 and I max this first.

Scrap Shield

Rumble creates a shield blocking 50 / 80 / 110 / 140 / 170 (+40% of ability power) incoming damage for 2 seconds, in addition Rumble receives a 10 / 15 / 20 / 25 / 30% movement speed boost for 1 second.

While in the "Danger Zone", the shield’s strength and movement speed boost are increased by 30%.

A invaluable asset though weak. At level one the shield can be used to get away and survive IGNITES yes the most annoying spell in game. Shields are the only thing that block true damage so use it wisely. If your low and see a karthus ult hit w and you should survive barely and then you can type LoL to all your teammates. It may look useless but the small speed and shield are pretty powerful. I level this at 3 once and max this last.

Electro-Harpoon

Rumble shoots a taser that deals 55 / 85 / 115 / 145 / 175 (+50% of ability power) magic damage and applies a 15 / 20 / 25 / 30 / 35% slow on the enemy hit for three seconds. A second shot can be fired for no additional cost within the next three seconds. The slows from these two tasers can stack with themselves and the duration will be refreshed with the second hit.

While in the "Danger Zone", the damage and slow percentage are increased by 30%.

Your only nuke spell in your spell setup. Though it scales the best and max look to do more damage it has a long cd and over time will do less damage than flame spitter. It slow is very useful early game and once you have your rylias and get two hits off on one person no one will survive. I level this at 2 and max this second.

The Equalizer

Rumble calls down a line of rockets over the target linear location, it uses click and drag targeting. The rockets deal an initial 150 / 225 / 350 (+50% of ability power) magic damage to all enemies hit on arrival, and also leave a trail of destruction for 5 seconds that slows by 35% and deals 120 / 160 / 200 (+25% of ability power) magic damage per second to all enemies standing on the area.

This ability does not generate heat.

This ability is probably one of the best in the game. It can be launched farther than the actually range circle says it can by facing it away from you at the edge. If you land a direct hit in the first second it can do the on hit plus the over time so at lvl 1 it can do 270, level 2 385 and level 3 550 with no ap. (This does not include magic pen vs armor ) At level 6 you should have harassed someone to low enough that this will insta kill them if not save it and harass just enough to get First blood or just a kill.

I take Marks of insight because all your offensive spells AND you passive do magic damage.
For seals i take Seals of vitality to increase late game survivability.
Then i take Glyphs of Celerity because Late game team fights you shall need to use abilities more often and this build has no CD items.
Finally i take Quints of fortitude for early game health.

I run a 9/21/0 off tank caster setup. This increases my durabilty and damage. Another possible combos on rumble are 9/0/21 but this will only allow you to have less death time and reduced cool down on flash and ignite with some regular cd for spell but if you play rumble right you shouldn't need all this cd or reduced deathtime.

Offensive:
I take the regular caster nine.
1 Deadliness and 3 archmage's Savy
4 Sorcery
1 Archaic Knowledge

The one in Deadliness allows into the second tier while the 3 in archmage's savy allow us more ap. Then Sorcery allows more CD along with our Glyphs. Finally Sorcery for magic pen.

Defense:
I take mostly regular tank setup but 3 in Ardor.
3 Resistance and 3 Hardiness
4 evasion
1 Nimbleness and 2 Harden skin
4 Veteran scars
3 Ardor
1 Tenacity

3 Resistance and 3 Hardiness allow us some armor and MR early game. 4 evasion gives us more dodge and allows us to get Nimbleness. Nimbleness gives us speed for a dodging which is helpful and 2 harden skin is basically like 1.5 armor. 4 Veteran Scars means another 100 health early game which means more lane sustain. 3 Ardor makes your late game ap scale even better. Finally 1 tenacity means more defense.

I start of with doran's shield. This provides you with some extra defence, health and most importantly HP Regen. Starting with a dorans ring gives you less health and no health regen and a useless mana regen stat so don't get it.

On your first trip back either pick up 1-2 items of rylias and/or boots 1. You should finish rylias then boots.

For boots you should either, depending on situation, get Sorc shoes, Ironian boots of swiftness or Merc treads. If they are builing Mr or are very tanky get Sorcs. If they are more health based and less defence based get Ionian for quicker damage. Then if their just focusing you hard with cc get merc treads instead because being cced means you can do as much damage.

Grabbing a Abysmall and Zhornas allows increased Mr and armor with great ap and other benifits. Abysmall MR reduction is Perfect for rumble because he is a melee caster and with a tiny bit of mr and ap it just synergizes well. Zhronas then prvides a ton of ap and great amount of armor and a great STASIS which if your being focused that means you pop this and can survive a burst or just delay it and force it on say you tank who is right
next to you.

Death cap is the only thing in this build in which it doesn't help more than one stat. It has great ap and increases the amount of ap you have by 15 percent and so you have a lot more power.

Guinsoo's may see like a item that's worthless but it actually is perfect for rumble. It increases your ability power and attack speed which makes your spells and PASSIVE! so much stronger. Being able to hit more often during overheat and make yourself stronger just by casting and autoing is really worth the item.

I won't say spell vamp isn't great but to me when i tried it spell vamp doesn't actully help till end game when everyone is nuking you because your a DoT based character but if would recommend spell vamp it would be hextech gunblade which will also include you autos and even though the other spell vamp item has a nice aura and currently the meta is 1 caster and if any other ap it would be the support so it wont help the team that much.

Summoner spells come to preference but also can hurt you if you don't use them right.

Guide Recommended:

Flash: I recommend flash because your w allows you to out speed most champions and the ability to change positions instantly is really strong. Also if you being chased hopping over a wall will usually allow you to survive or at least burn the enemy's flash for your team to come kill them after they kill you.

Ignite: I recommend ignite because your main damage is DoT and healers can be annoying. This spell scales perfectly with your main damage out put and removes pesky heals that would allow someone to save themselves usually.

Recommend:

Ghost: Though i don't prefer this Ghost plus W can get you away fast and it is on shorter cd. But it isn't a instant change of position and most nukers can get you if you ghost with cc.

Exhaust: You can put a point in it instead of Toughness and it will slow and lower mr and armor. Early game this will be great but late game you will have more slow than this will so it will be only could to lower attack speed and defense stats.

Heal: Useful for FB or early game lane sustain. But it does not scale into late game and so it becomes useless.

Teleport: Great map mobility but does not allow you to escape or do more damage. Using q and e then w out of spawn and spamming w should get you to lane quickly and efficiently without this spell but if you prefer it go ahead.

Clense: If your feel the enemy will have a TON of cc or hate cc in generally you can take this.

Most other spells are useless or for different roles.

In lane you should be last hitting and harassing. DO NOT q spam minions this will push your lane and get you ganked over and over and over. Using flame spitter every now and then is ok against some champs like morde. If facing ranged and strong early game opponents last hit with e and wait for times when you can burst them hard. As earlier i stated at 6 once you have your ult you should be able to kill a opponent if he hasn't recalled once. Rumble is most efficient solo top for doran shield gives him health regen and thats all he needs to sustain in lane. Also be doing 1 of this 2 things at all times. Getting kills or FARMING. Rumble is gold dependent and your must either have a ton of kills or a ton of CS. If duo laning you should try to harass the oppenents and let the carry farm or if you are the carry of that lane try to farm then harass.

9-4-11
First Major update!
Completely reworked the guide from the useless information about a build into a more organized and explanatory guide.