Okay, I've done some testing based on the advice above regarding spamming Dark Restoration. If you keep doing this, Dark Restoration spell will change to Dark Embodiment. At that point, every time you cast it, you should see (in addition to HP and Mana gain):
Attack +1 Defense +2
M. Attack +1 M. Defense +2
Agility +2 Luck +0
It also gives you 50 Mana story points per cast. When you hit 500, you use Mana Refinement spell and you get an additional:
Attack +10 Defense +20
M. Attack +10 M. Defense +20
Agility +20 Luck +0
So, I'm currently in my room, spamming the spell over and over to get to the point of where I can survive the 4 archers in the tournament.
Thank you for the great tip DaedusWolfe!
P.S. At some point, I run out of mana and can no longer case the spell -- it's grayed out. Simply rest in bed and it resets and allows more casts. Just FYI in case anyone runs into this.