When can the Resist Pain spell be cast? It claims the users endorphine levels are boosted, so couldn't it be cast prior to taking damage and have the spell work for the first set of injuries incurred, within so much time of being cast?

I am thinking about the TN modifiers that accumulate during an astral quest. Could the mage cast this during his quest (it's a mana spell)?

Could a secong mage cast it on the projecting mages physical body when it manifests the injuries?

Scanning through the description of the spell, I would say that it can't be cast before the damage is incurred for the simple reason that there is no damage to resist. The endorphine levels are boosted to counter the damage, and if there's no damage then the endorphine levels won't rise. It's just not how the spell works. If it would work that way, it would have been a sustained spell, instead of a permanent one, which is, of course, another reason to rule against casting it before; the spell dissipates when the character heals his or her wounds, if there are no wounds to heal the spell would dissipate immediately.