Up until now the particles have been uniform in size and don't fade away, Change their size and add some cool visual effects to make it seem like the particles dissipate after traveling a small distance.
Head to the “when I receive hit” block and the Purple Looks tab. Grab a "set ___ effect to __" block and put one below the "show" block. Then add a second.
Like the last step, grab a "change ___ effect by ___" block and adjust it to change "pixelate" and it's value to be 2. If you test it can you see a difference between this and the last step?