While using Brigitte in Stadium with Hardlight Accelerator, Brigitte is supposed to get a single stack after using Shield Bash. Spamming the left click ( BASH ) will cause it to give additional charges. Although in a short time frame, I was able to get 3 stacks of Hardlight Accelerator consistently by left-clicking 3 times consecutively.
This also did not seem to work with other heroes, from what I have tested.