Laserlike Attack for Custom Mob

Hey there!

For a dimension I created I want custom mobs that float and shoot laser-like attacks at the player. I have no Idea on how to do this.

I created the Mob with texture and made it fly, but I want a Laser-like attack. I want it to either have the guardian laser attack or another custom attack in which it looks at the player, tracks a straight line to him(I want to fill the line with particles then) and then damages the player

thanks for help in advance