That sounds fine if you take a standard action to aim the drop. Doing it as a minor action should probably be less damage, a lower hit probability, or both.Intelligence based attack vs Reflex, with damage of 1d10+3. Roughly comparable with magic missile, except it takes more trouble to set up. It can be useful for ambushes though, so nobody knows where the shot came from.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.