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.
Rumble's basic abilities generate 20 Heat when used. When Rumble reaches 50 Heat, he is in the Danger Zone, causing all of his basic abilities to have enhanced effects. When Rumble reaches 100 Heat he overheats for 6 seconds; during this time he may not use his own abilities, but all his basic attacks deal additional magic damage. While not overheated, after 4 seconds of not using his basic 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.
When Rumble reaches 100 Heat he overheats for 6 seconds. While overheated Rumble cannot use his own spells, but his basic attacks deal an additional 20 + (5 × level) (+ 25% AP) magic damage. Rumble's Heat is reset to 0 after the overheat effect ends.
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 (dealing half damage to minions). Rumble can perform other actions while Flamespitter is active.
Active: 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. If the second taser slows an enemy that has been slowed by the first, the slow is refreshed and its movement speed reduction is doubled.
Active: Rumble calls down a line of rockets over the target linear location, 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%.
Area Magic Damage Per Second: 130 / 185 / 240 (+ 30% AP)