The items I have chosen in this build and the order, to get them, all depend on who you are against in solo top/duo top and how familiar you are with the champion Rumble. If you are against a solo top that is mostly melee, you would want to choose items that could help you set up for a fight. Choosing Rylai's will help you harass with your E and slowing the enemy so it will be easier for the jungler to gank. Getting an early game Haunting Guise, for the health and Magic Penetration will help you survive fights while dealing out an insane amount of damage. After you get Haunting Guise, you will want to look into some more mobility to chase down enemies or run away from fights that aren't turning in your favor. Remember to get an early Abyssal Scepter to help you take damage from the enemy AP Caster while dealing a great amount of damage of your own. Rabadon's Deathcap will help increase the damage you deal by a ton. Increasing your AP by 140 + 30% of what it is already. Next try and get Zhonya's Hourglass to help take some damage from the enemy's AD champions, and getting an extra boost of 100 AP, plus a very helpful Unique Active. Which makes your champion invincible for 2 seconds, however, you are unable to take any action in this form. When/If the enemies start to build a lot of Magic Resist, sell your Haunting Guise to pick up a Void Staff. Which will shred through the enemies defenses a lot quicker then Haunting Guise would. (If any of these items do not work well with the opposing team, be sure to switch them out for items that will work better.

The Masteries I have chosen are for some early game Ability Power, Cooldown Reduction, and Magic Penetration. Some bonus ability power early game sure can get the extra edge on the opponent when you dish out a lot of damage. Cooldown Reduction works great with Rumble, because he is not restricted by mana and it is very easy for Rumble to spam abilities. Magic Penetration early will help you win battles because usually, the enemy Magic Resist off start is pretty low. Usually giving 20%-30% reduced magic damage, depending on who you are solo top against.

For Runes, i like to run heavy Ability Power and Magic Penetration, and getting a little lead in the Health as well. Getting Ability Power and Magic Penetration runes will GREATLY increase the damage you dish out to your enemy in scrimmages in top lane, and give you the extra boost you need to take an enemy down. The Health Runes will also help in fights, because they will give you a few extra points in health, which could help out more than you think. (However, feel free to switch out Runes for your style of gameplay and your build.)

The Skill Sequence I chose, will give you good harassment with your Electro Harpoon and good damage in your Flamespitter as well. I feel it is better to max one move at a time, because it can increase the damage you deal in early game fights greatly. While using his Electro Harpoon and Flamespitter to dish out a lot of damage, using Scrap Shield can give you the extra speed boost you need to chase down, or escape an enemy. Using Electro Harpoon on the same target twice, or two separate targets, will slow the enemies movement speed which can set you up for an amazing Ultimate. The Equalizer is a key factor in any team fight. Try taking your time in selecting on where you would like it to go, and which area would be more effective, not only for teamfights, but also cutting off enemies escape routes. The Equalizer can make or break teamfights, use it wisely.

For Summoner Spells, i like to go Flash and Ignite which can help you escape and kill high priority targets. Although, feel free to switch out Flash for Ghost which is another great tool for escapes or chasing down a stray enemy. (Make sure to take exhaust though instead of ignite if your team mates do not have an exhaust, because a Ranged Carry or a Melee Carry can be very scary if you are not prepared for the fight.)

I have already mentioned most of the tactics Rumble has to help an injured ally to escape, or to help in fights. Make sure to use Electro Harpoon if you or an ally are getting chased. Use The Equalizer to help greatly in team fights, but make sure you choose wisely on where to put it, cutting off someones escape, or simply using it in the middle of a fight which can have a great effect on the fight and will turn it in your favor.

Using Flamespitter is Rumble's best way to kill creeps. However, it deals reduced damage to minions, but can still deal a large amount of damage to a number of creeps, making it easier to last hit them.