If wraiths shoot two projectiles each shot in your stand alone game just as they do in SCII, you could consider having both projectiles fire towards the cursor, instead of in a straight forward path. Thus, the two projectiles would cross at the position of the cursor when the shots were fired. This opens up the opportunity to either focus fire or shoot in two different directions at once (if the cursor is very near the wraith), but shooting in two directions requires a dexterous hand.
I programmed a 2-dimensional game a little while ago that uses a parametric equation to position the projectiles initially, and then their direction is set towards the cursor. After that, they just keep going in a straight line, towards where the position of the cursor when they were initially fired. I attached a picture of it; notice how the lines cross. You can easily adjust the distance of where they cross simply by moving your cursor. I will copy and paste the code with an explanation if you request
