Let me help you with that!
What you want to do is make an impact frame or two to insinuate the flashbang going off, I can make an example in the WB. Or you can refer to the Impact frame I already made for the Nuke Exploding, also in the WB.
Yeah! He almost got me too, but luckily, I was able to detect sound waves reaching across the ever expanding void insinuating his identity. I also read his username, but it was mostly the first part.