Priest is the only class without a spell or attack that does good damage against single targets, like dark bear or cyclops, in PvE. Since virtually all monsters above level 100 are immune to Life Drain, Rage Light Ball is the best thing priests have for single target damage. Rage Light Ball however, is slow, cost too much divine, and does too little damage that priest might as well use Charisnumen Authority instead, even against a single monster. This is a big problem because it takes priest forever to hunt for dual quest items such as skin and secret.
I think Rage Light Ball should do 2x as much damage, and cost half as much divine, since right now the spell is laughable. This way Priest can get some Orison tactic at Dark Bear or Cyclops, and also make it a lot easier for priest to hunt things like Secret Document for dual quests and Bear/Cyclops for skin.
No, this wouldn't make Rage Light Ball overpowered. Even with 120 Orison and g3 nature vigor my Rage Light Ball still only does 13500 damage to tactic dummy, but my mage with 100 Magery does 17200 damage per Firebird hit, so twice as much damage would mean Rage Light does about the same, maybe slightly more, than 1 firebird hit. Rage Light Ball would still be too weak and slow to kill anyone in PvP, unless they aren't even Crossing Class yet, but it would be useful enough to hunt dual items and get tactic from dark bear, cyclops, etc.