Current Behaviour
The Marksman passive Rain of Arrows procs a single hit of an unmodified Rain of Arrows ability at most once every 10 seconds with four points invested.
Problem
For a minimum total of 6 passive points, fully 5% of all passive points available to a level 100 character, all we get is a single hit (AoE) of an unmodified RoA. For a character who is scaling physical damage, this isn’t so bad, but for a character that is scaling any other damage type, this investment is likely a DPS loss, or at the very least just lackluster.
Solution
Allow the RoA passive to use the RoA skill tree, and to cost commensurate mana when it does so. This would allow the hit from the passive to use the correct damage type scaling for any build.
Other Considerations
Since the RoA passive procs only a single hit of the RoA skill, and not a full volley, the amount of mana the proc costs should be reduced to compensate. For example, if your RoA tree would normally cause RoA to hit 4 times during its duration, then the proc should cost one fourth of the normal total mana cost of the skill.