Effect effect = Effect.COLOURED_DUST;
Location pointA = attacker.getEyeLocation();
Location pointB = attacker.getEyeLocation().add(attacker.getEyeLocation().getDirection().normalize().multiply(5));
int numberOfPointsBetweenAAndB = 10;

World tempWorld = pointA.getWorld();
int timeIterated = 0;
double xIncrement = 0.0D;
double yIncrement = 0.0D;
double zIncrement = 0.0D;
double currentX = 0.0D;
double currentY = 0.0D;
double currentZ = 0.0D;

VisibleCheck:
for (int i = 0; i < numberOfPointsBetweenAAndB; i++) {
    if (timeIterated > numberOfPointsBetweenAAndB) {
        return;
    }
    if (timeIterated == 0) {
        currentX = pointA.getX();
        currentY = pointA.getY();
        currentZ = pointA.getZ();
        xIncrement = (currentX - pointB.getX()) / numberOfPointsBetweenAAndB;
        yIncrement = (currentY - pointB.getY()) / numberOfPointsBetweenAAndB;
        zIncrement = (currentZ - pointB.getZ()) / numberOfPointsBetweenAAndB;
        Location thisLoc = new Location(tempWorld, currentX, currentY, currentZ);

        Block block = tempWorld.getBlockAt(thisLoc);

        tempWorld.playEffect(thisLoc, effect, 0);

        timeIterated++;
    } else {
        currentX -= xIncrement;
        currentY -= yIncrement;
        currentZ -= zIncrement;
        Location thisLoc = new Location(tempWorld, currentX, currentY, currentZ);

        Block block = tempWorld.getBlockAt(thisLoc);

        tempWorld.playEffect(thisLoc, effect, 0);
        timeIterated++;
    }
}