I swear that I saw a runepriest feat or spell that caused over healing to become temporary hit points. Am I losing my mind, or does such a thing exist?
Rune of Hope [Rune]
Heroic Tier
Prerequisite: Runepriest, rune of mending power
Benefit: The target of your rune of mending also gains temporary hit points equal to the number of rune feats you have.
Not that that's very much. I don't see any attack powers that do that. And, frankly, it's not like runepriests are going to be likely to overheal much.
There was a belt that allowed you to keep overhealing as tHP. I forget the name.