Rumble Bug
6.4 patch notes, BABY DON'T FAIL ME NOW If Rumble overheats using Electro Harpoon, he’ll always be able to fire while silence as long as he has 1 charge (same as live)
Currently if you overheat using any other ability with 1 harpoon stack you can still use harpoons whilst overheated.
To create this bug, get to 80+ heat, use Q or W whilst only having 1 harpoon stack, you will now be able to use your 1 stack** plus **the extra stack that will recharge during your overheating phase.