Out of combat hunter mana script

[Nolife]

I think you should be able to run something like:

/script if (UnitPower("player") / UnitPowerMax("player") < 0.5 ) then CastSpellByName("Aspect of the Viper"); else CastSpellByName("Aspect of the Hawk"); end

I'm at work so can't test any scripts. That's just something off the top of my head...