Honestly, I planned on Mana tanking to not count in the gold reward initially, and I'm still up in the air about it. Maybe I should make the Mana Shield abilities only tank 50% of the damage? That would give some benefit. But if I added the Mana damage taken to the gold rewarded, than I could NEVER allow a rapid firing gun. It would just be too much stacking.
Although, a Mana replenishing Shot isn't a bad idea, and I don't remember thinking of it, so I will certainly write it down and hopefully get to it by the next release.