| CuzImAwesome |
It seems like that class is based heavily on direct connection to higher beings or gods. What I would do it look back on people in different religions that filled that role and see if any of their terms fit. The description you gave fits a traditional shaman of Norther Asian history but since we already have a class named after that it probably wouldn't fit. Vessel was already suggested which works well but I would try to find something with a little more impact and weight behind it.
"Herald" may fit, they were messengers of higher power (like that positive energy plane) and omens of great change. If you went this way you could also make them kind of polarizing among a society where some people see them as bringers of prosperity and others see them as symbols of destruction. If I were making this class, I'd use this.