One thing is that if one is moving around while firing the laser, its origin point will be the staff’s spawn point at the time the attack was triggered but not where the spawn point is when it actually fires.
Also, if one is close by some foreground layer tiles (standing right in front of the hills), the laser’s range might be severly shortened when firing “downwards” but on the other hand the obstruction in its path is not correctly detected when firing “upwards” and one can still manage to fire across the obstacle…