How would I create a laser beam of sorts

Alright, so basically, I want to do make some sort of laser, I have messed about a bit and all I found out how to do is check if you're looking at a block. I can get the direction of the block but idk how to interact with it, as if it checks: "Is <Event/target  entity> looking at a block with raytrace distance (5) fluid mode [ANY] block mode [OUTLINE]", and if so Explode at x: <x position of block at <Look X position of <Event/target  entity> with raytrace distance (5) fluid mode [ANY] block mode [OUTLINE]>> and so on for x, y, and z. How would I do this? Also, could I do something similar with Entities? so locate them and for example damage them with a custom damage thingy.