I'm noticing a potential bug on a spell I tend to use quite a bit. With the level 5 energy orb, I'm noticing it getting stuck on horizontal surfaces quite a bit. It seems to happen almost exclusively when firing toward the left hand side of the screen at an angle, so the orb would sweep along the ground or ceiling, it just stops. When firing to the right, it also seems to get stuck occasionally, but only momentarily, then continues as expected.
Edit: It seems to happen with other spells that traditionally followed the contours of the land.