Commendable for trying to take a criticism in stride to make improvements, but how exactly is this useable feedback to make changes? What did he mean by "using too much mana"? Should you have done less and let people die? Then the complaint would have been you didn't do enough. This rings true:

Quote Originally Posted by Sinaloa View Post
You can rezz to much or cast succ too often. But at the end of the day that's often not your choice if you have to.
You can't really control how much mana you'll have to burn to keep people alive and in the fight. The only choice in the matter if have is how much you DPS and overheal...even then DPSing is really the only thing you singularly have control over. If you're in a large group and both healers choose to heal the same target, overhealing is going to happen.

This guy was just upset things weren't going right and was taking it out on his party. Take what he said as a footnote, not as a serious complaint about how well you do what you do.