Rumble's abilities have no cost related to them, and the use of his abilities is only limited by cooldowns. Instead, he uses HEAT as his secondary resource. Rumble starts with 0 HEAT, and it caps at 100.
While not overheated, after 4 seconds of not using his abilities he will start losing HEAT at a rate of 10 HEAT per second, then at a rate of 20 HEAT per second 2.5 seconds later.
Rumble's basic abilities generate 20 HEAT when used.
Danger Zone - 50-99 HEAT: Rumble's basic abilities temporarily have enhanced effects.
Overheating - 100 HEAT: Rumble's spells are disabled for 6 seconds, but his basic attacks deal an additional 「 20 + (5 × Rumble's level) 」「 25 / 30 / 35 / 40 / 45 / 50 / 55 / 60 / 65 / 70 / 75 / 80 / 85 / 90 / 95 / 100 / 105 / 110 」(+ 25% AP) magic damage over the duration. Rumble's Heat resets to 0 after the effect ends.
Junkyard Titan is composed of two separated effects.
Although it visually appears as and is termed a silence, overheating does not prevent Rumble from using summoner spells or item actives, only his own spells. The exception is the second cast of Electro-Harpoon, assuming the first cast overheats him.
Active: Rumble activates his flamethrower for 3 seconds, dealing magic damage every 0.5 seconds to enemy units in a cone in front of him (half to minions and neutral monsters). Rumble can perform other actions while Flamespitter is active.
Scrap Shield has no cast time and does not interrupt Rumble's previous orders. It does however cancel his basic attack animation.
First Cast: Rumble shoots a taser that deals magic damage and applies a slow on the first enemy it hits for 3 seconds. A second shot can be fired for no additional cost within the next 3 seconds, even if Rumble overheats.
Second Cast: Same effects as the first active. If both tasers hit the same target, the slow duration is refreshed and its movement speed reduction is doubled.
Unlike all other forms of slow stacking, two harpoons on the same target will have their slows calculated additively.
Movement speed cannot be reduced below 110, and that slows that would reduce below 220 are modified. To put it another way: a reduction of 105% will not reduce you to 0 movement speed, but rather it will reduce you closer to 110 than a weaker slow would.
Each cast counts as a separate spellcast for the purposes of abilities such as Force Pulse and Sheen.
COOLDOWN: 105 / 90 / 75
Active: Rumble calls down a line of rockets over a 1000-length area, using a click and drag targeting system.
The rockets leave a trail of destruction for 5 seconds, dealing magic damage every second and slowing all enemies standing on the area by 35%.