I love it! Except for the fact that you offered it to life. It would also make balance the best pvp school to have and therefore it would have to be balanced out by utilities for the other schools. For example life could decrease backlash on a target. Storm could increase it on the enemy and so on.
If you are going to make a spell to remove shadow pips it should cost a power pip as well. Make it 1 power pip (2 regular) + 1 shadow pip for all schools. No damage.
Effect: Deals 300 damage per pip to target and remove 1 pip.
Took the idea from Mana Burn. This might help counter the shadow spells
or
School: or
Cost: 3 Pips
Accuracy: 60%
Effect: Deals 100 damage to target, and remove all shadow effects on the target and applies Backlash.
This one from Supernova.
What do you guys think?
The only problem is that, A: That makes shadow magic completely useless. B: Promethean and Exalted PVP Will be ruined by balance and life. And C: Its Kinda Op. Imagine using the supernova shadow spell on the turn someone casts shrike or something. They'll get wrecked by the 30 backlash.
or 
damage per 
