I have been playing my holy priest with a ret in 3v3 lately, and have discovered this amazing exploit.
If you are about to die vs a caster team, have your paladin BoP you.
You will die and go into spirit of redemption form.
All your buffs will still be active during spirit form.
Right click the spirit of redemption buff. You are now supposed to die, but BoP will absorb the damage.
You are now back to life and have full mana as a bonus.
I dont do PvE but it might have some uses there aswell. For example the
priest is oom and the group is dying to aoe damage, the priest can stop
healing himself, get a BoP and die, then return with full mana and hp.