Works also for GM:S2. It's not creating new objects or particle system but use draw_sprite_ext, what should be WAY more efficient. A proper afterimage trail effect that shows the right sprite image that was active at the moment. Control how many images you want and an interval. It consists of scripts in create, step and draw events that take care of trail and all it needs is a switch to trigger (like button hold). Scripts have comments for easy understanding what's going on and they are easy to expand.